v26.0.0

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Breaking Changes

• Eventlet worker removed: The eventlet worker class has been dropped. Migrate to gevent, gthread, or tornado.

New Features

• ASGI Framework Compatibility Suite: New end-to-end compatibility test harness covering Starlette, FastAPI, Litestar, Quart, Sanic, and BlackSheep. Current grid passes 438/444 tests (98%).
• ASGI Test Suite Expansion: 134 additional ASGI unit tests covering protocol semantics, lifespan, websockets, and chunked framing.

Security

• HTTP/1.1 Request-Target Validation (RFC 9112 sections 3.2.3, 3.2.4):
  • Reject authority-form request-target outside CONNECT
  • Reject asterisk-form request-target outside OPTIONS
  • Reject relative-reference request-targets
• Header Field Hardening (RFC 9110):
  • Reject control characters in header field-value (section 5.5)
  • Reject forbidden trailer field-names (section 6.5.1)
  • Reject Content-Length list form (RFC 9112 section 6.3)
• Request Smuggling Hardening:
  • Tighten keepalive gate and scope finish_body byte cap
  • Keep _body_receiver alive across the keepalive smuggling gate so pipelined requests cannot re-enter a closed body
  • Address parser/protocol findings from a six-point WSGI/ASGI audit
• PROXY Protocol (ASGI): Enforce proxy_allow_ips and tighten v1/v2 parsing in the ASGI callback parser.
• Connection Draining: Drain the connection on close per RFC 9112 section 9.6 to prevent reset-on-close truncation.

Bug Fixes

• Body Framing on HEAD/204/304:
  • Keep Content-Length on HEAD and 304 responses (#​3621)
  • Drop body framing on HEAD/204/304 even when the framework set it
  • Warn once when an ASGI app emits a body for a no-body response
• HTTP/2 ASGI:
  • Fix _handle_stream_ended to set _body_complete in the async HTTP/2 handler so request bodies finalize correctly on stream end
  • Add InvalidChunkExtension mapping and fast-parser support in ASGI tests (#​3565)
• HTTP/1.1 100-Continue: Stop adding Transfer-Encoding: chunked to 100-Continue interim responses.
• WebSocket Close Handshake (RFC 6455):
  • Comply with the close handshake state machine
  • Close the transport after the close handshake completes
  • Fix binary send when the text key is None
• Early Hints: Validate headers in the early_hints callback to match process_headers; pass only the header name to InvalidHeader (#​3588).
• ASGI Framework Fixes:
  • Fix ASGI disconnect handling for Django-style apps
  • Fix Litestar request handling (use raw ASGI receive for body/headers)
  • Fix Litestar HTTP endpoints for compatibility tests
  • Fix Quart headers endpoint to normalize keys to lowercase
  • Fix Quart WebSocket close test app (missing accept())
  • Fix duplicate Transfer-Encoding header for BlackSheep streaming

Refactoring

• Split BodyReceiver._closed into separate transport and body-wait flags for clearer keepalive/EOF semantics.

Changes

• Fast HTTP Parser: Require gunicorn_h1c >= 0.6.5. Drop the last python_only test markers; the C extension is now used wherever available (CPython only; PyPy continues to use the Python parser).
• Test Dependencies: Add h2 and uvloop to the testing extra; remove eventlet.
• Docker Build: Bump GitHub Actions docker/setup-qemu-action, docker/setup-buildx-action, docker/login-action, docker/build-push-action, and docker/metadata-action to current major versions.

Full changelog: benoitc/gunicorn@25.3.0...26.0.0

v25.3.0: Gunicorn 25.3.0

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Bug Fixes

• HTTP/2 ASGI Body Duplication: Fix request body being received twice in HTTP/2
  ASGI requests, causing JSON parsing errors with "Extra data" messages
  (#​3558)

• ASGI Chunked EOF Handling: Add finish() method to callback parser to handle
  chunked encoding edge case where connection closes before final CRLF after zero-chunk

• HTTP/2 Documentation: Fix http_protocols examples to use comma-separated string
  instead of list syntax (#​3561)

• Chunked Encoding: Reject chunk extensions containing bare CR bytes per RFC 9112
  (#​3556)

• Request Line Limit: Fix --limit-request-line 0 to mean unlimited as documented,
  instead of using default maximum. Works with both Python and fast C parser.
  (#​3563)

Security

• ASGI Parser Header Validation: Add security checks per RFC 9110/9112:
  • Reject duplicate Content-Length headers
  • Reject requests with both Content-Length and Transfer-Encoding
  • Reject chunked transfer encoding in HTTP/1.0
  • Reject stacked chunked encoding
  • Validate Transfer-Encoding values
  • Strict chunk size validation

Changes

• Fast HTTP Parser: Update to gunicorn_h1c >= 0.6.3 for asgi_headers property
  and InvalidChunkExtension validation for bare CR rejection

• ASGI PROXY Protocol: Add PROXY protocol v1/v2 support to callback parser

• Docker Images: Update to Python 3.14

v25.2.0: Gunicorn 25.2.0

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New Features

• Fast HTTP Parser (gunicorn_h1c 0.4.1): Integrate new exception types and limit parameters from gunicorn_h1c 0.4.1 for both WSGI and ASGI workers
  • Requires gunicorn_h1c >= 0.4.1 for http_parser='fast'
  • Falls back to Python parser in auto mode if version not met
  • Proper HTTP status codes for limit errors (414, 431)

Bug Fixes

• uWSGI Async Workers: Fix InvalidUWSGIHeader: incomplete header error when using gevent or gthread workers with uwsgi protocol behind nginx. (#​3552, PR #​3554)

• FileWrapper Iterator Protocol: Add __iter__ and __next__ methods to FileWrapper for full PEP 3333 compliance. (#​3396, PR #​3550)

Performance

• ASGI HTTP Parser Optimizations: Improve ASGI worker HTTP parsing performance
  • Callback-based parsing with direct bytearray buffer operations
  • Use bytearray.find() directly instead of converting to bytes first
  • Use index-based iteration for header parsing instead of list.pop(0) (O(1) vs O(n))

v25.1.0: Gunicorn 25.1.0

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New Features

• Control Interface (gunicornc): Add interactive control interface for managing
  running Gunicorn instances, similar to birdc for BIRD routing daemon
  (PR #​3505)

  • Unix socket-based communication with JSON protocol
  • Interactive mode with readline support and command history
  • Commands: show all/workers/dirty/config/stats/listeners
  • Worker management: worker add/remove/kill, dirty add/remove
  • Server control: reload, reopen, shutdown
  • New settings: --control-socket, --control-socket-mode, --no-control-socket
  • New CLI tool: gunicornc for connecting to control socket
  • See Control Interface Guide for details

• Dirty Stash: Add global shared state between workers via dirty.stash
  (PR #​3503)

  • In-memory key-value store accessible by all workers
  • Supports get, set, delete, clear, keys, and has operations
  • Useful for sharing state like feature flags, rate limits, or cached data

• Dirty Binary Protocol: Implement efficient binary protocol for dirty arbiter IPC
  using TLV (Type-Length-Value) encoding
  (PR #​3500)

  • More efficient than JSON for binary data
  • Supports all Python types: str, bytes, int, float, bool, None, list, dict
  • Better performance for large payloads

• Dirty TTIN/TTOU Signals: Add dynamic worker scaling for dirty arbiters
  (PR #​3504)

  • Send SIGTTIN to increase dirty workers
  • Send SIGTTOU to decrease dirty workers
  • Respects minimum worker constraints from app configurations

Changes

• ASGI Worker: Promoted from beta to stable
• Dirty Arbiters: Now marked as beta feature

Documentation

• Fix Markdown formatting in /configure documentation

v25.0.3

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What's Changed

Bug Fixes

• Fix RuntimeError when StopIteration raised in ASGI coroutine (#​3484)
• Fix passing maxsplit in re.split() as positional argument (deprecated in Python 3.13)

Documentation

• Updated sponsorship section and homepage

Full Changelog: benoitc/gunicorn@25.0.2...25.0.3

v25.0.2: Release 25.0.2

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Bug Fixes

• Fix ASGI concurrent request failures through nginx proxy by normalizing
  sockaddr tuples to handle both 2-tuple (IPv4) and 4-tuple (IPv6) formats
  (PR #​3485)

• Fix graceful disconnect handling for ASGI worker to properly handle
  client disconnects without raising exceptions
  (PR #​3485)

• Fix lazy import of dirty module for gevent compatibility - prevents
  import errors when concurrent.futures is imported before gevent monkey-patching
  (PR #​3483)

Changes

• Refactor: Extract _normalize_sockaddr utility function for consistent
  socket address handling across workers

• Add license headers to all Python source files

• Update copyright year to 2026 in LICENSE and NOTICE files

v25.0.1

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Bug Fixes

• Fix ASGI streaming responses (SSE) hanging: add chunked transfer encoding for
  HTTP/1.1 responses without Content-Length header. Without chunked encoding,
  clients wait for connection close to determine end-of-response.

Changes

• Update celery_alternative example to use FastAPI with native ASGI worker and
  uvloop for async task execution

Testing

• Add ASGI compliance test suite with Docker-based integration tests covering HTTP,
  WebSocket, streaming, lifespan, framework integration (Starlette, FastAPI),
  HTTP/2, and concurrency scenarios

v25.0.0: Gunicorn 25.0.0

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New Features

• Dirty Arbiters: Separate process pool for executing long-running, blocking
  operations (AI model loading, heavy computation) without blocking HTTP workers
  (PR #​3460)

  • Inspired by Erlang's dirty schedulers
  • Asyncio-based with Unix socket IPC
  • Stateful workers that persist loaded resources
  • New settings: --dirty-app, --dirty-workers, --dirty-timeout,
    --dirty-threads, --dirty-graceful-timeout
  • Lifecycle hooks: on_dirty_starting, dirty_post_fork,
    dirty_worker_init, dirty_worker_exit

• Per-App Worker Allocation for Dirty Arbiters: Control how many dirty workers
  load each app for memory optimization with heavy models
  (PR #​3473)

  • Set workers class attribute on DirtyApp (e.g., workers = 2)
  • Or use config format module:class:N (e.g., myapp:HeavyModel:2)
  • Requests automatically routed to workers with the target app
  • New exception DirtyNoWorkersAvailableError for graceful error handling
  • Example: 8 workers × 10GB model = 80GB → with workers=2: 20GB (75% savings)

• HTTP/2 Support (Beta): Native HTTP/2 (RFC 7540) support for improved performance
  with modern clients (PR #​3468)

  • Multiplexed streams over a single connection
  • Header compression (HPACK)
  • Flow control and stream prioritization
  • Works with gthread, gevent, and ASGI workers
  • New settings: --http-protocols, --http2-max-concurrent-streams,
    --http2-initial-window-size, --http2-max-frame-size, --http2-max-header-list-size
  • Requires SSL/TLS and h2 library: pip install gunicorn[http2]
  • New example: examples/http2_gevent/ with Docker and tests

• HTTP 103 Early Hints: Support for RFC 8297 Early Hints to enable browsers to
  preload resources before the final response
  (PR #​3468)

  • WSGI: environ['wsgi.early_hints'](headers) callback
  • ASGI: http.response.informational message type
  • Works with both HTTP/1.1 and HTTP/2

• uWSGI Protocol for ASGI Worker: The ASGI worker now supports receiving requests
  via the uWSGI binary protocol from nginx
  (PR #​3467)

Bug Fixes

• Fix HTTP/2 ALPN negotiation for gevent and eventlet workers when
  do_handshake_on_connect is False (the default). The TLS handshake is now
  explicitly performed before checking selected_alpn_protocol().

• Fix setproctitle initialization with systemd socket activation
  (#​3465)

• Fix Expect: 100-continue handling: ignore the header for HTTP/1.0 requests
  since 100-continue is only valid for HTTP/1.1+
  (PR #​3463)

• Fix missing _expected_100_continue attribute in UWSGIRequest

• Disable setproctitle on macOS to prevent segfaults during process title updates

• Publish full exception traceback when the application fails to load
  (#​3462)

• Fix ASGI: quick shutdown on SIGINT/SIGQUIT, graceful on SIGTERM

Deprecations

• Eventlet Worker: The eventlet worker is deprecated and will be removed in
  Gunicorn 26.0. Eventlet itself is no longer actively maintained.
  Please migrate to gevent, gthread, or another supported worker type.

Changes

• Remove obsolete Makefile targets
  (PR #​3471)
• Replace RST with markdown documentation format

v24.1.1

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Bug Fixes

• Fix forwarded_allow_ips and proxy_allow_ips to remain as strings for backward
  compatibility with external tools like uvicorn. Network validation now uses strict
  mode to detect invalid CIDR notation (e.g., 192.168.1.1/24 where host bits are set)
  (#​3458,
  PR #​3459)

Full Changelog: benoitc/gunicorn@24.1.0...24.1.1

v24.1.0: Gunicorn 24.1.0

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New Features

• Official Docker Image: Gunicorn now publishes official Docker images to GitHub Container Registry (PR #​3454)

  • Available at ghcr.io/benoitc/gunicorn
  • Based on Python 3.12 slim image
  • Uses recommended worker formula (2 × CPU + 1)
  • Configurable via environment variables

• PROXY Protocol v2 Support: Extended PROXY protocol implementation to support the binary v2 format in addition to the existing text-based v1 format (PR #​3451)

  • New --proxy-protocol modes: off, v1, v2, auto
  • auto mode (default when enabled) detects v1 or v2 automatically
  • v2 binary format is more efficient and supports additional metadata
  • Works with HAProxy, AWS NLB/ALB, and other PROXY protocol v2 sources

• CIDR Network Support: --forwarded-allow-ips and --proxy-allow-from now accept CIDR notation (e.g., 192.168.0.0/16) for specifying trusted networks (PR #​3449)

• Socket Backlog Metric: New gunicorn.socket.backlog gauge metric reports the current socket backlog size on Linux systems (PR #​3450)

• InotifyReloader Enhancement: The inotify-based reloader now watches newly imported modules, not just those loaded at startup (PR #​3447)

Bug Fixes

• Fix signal handling regression where SIGCLD alias caused "Unhandled signal: cld" errors on Linux when workers fail during boot (#​3453)
• Fix socket blocking mode on keepalive connections preventing SSL handshake failures with async workers (PR #​3452)
• Use smaller buffer size in finish_body() for faster timeout detection on slow or abandoned connections (PR #​3453)
• Handle SSLWantReadError in finish_body() to prevent worker hangs during SSL renegotiation (PR #​3448)
• Log SIGTERM as info level instead of warning to reduce noise in orchestrated environments (PR #​3446)
• Print exception details to stderr when worker fails to boot (PR #​3443)
• Fix unreader.unread() to prepend data to buffer instead of appending (PR #​3442)
• Prevent RecursionError when pickling Config objects (PR #​3441)
• Use proper exception chaining with raise from in glogging.py (PR #​3440)

Installation

pip install gunicorn==24.1.0

Or use the official Docker image:

docker pull ghcr.io/benoitc/gunicorn:24.1.0

v24.0.0

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New Features

• ASGI Worker (Beta): Native asyncio-based ASGI support for running async Python frameworks like FastAPI, Starlette, and Quart without external dependencies

  • HTTP/1.1 with keepalive connections
  • WebSocket support
  • Lifespan protocol for startup/shutdown hooks
  • Optional uvloop for improved performance

• uWSGI Binary Protocol: Support for receiving requests from nginx via uwsgi_pass directive

• Documentation Migration: Migrated to MkDocs with Material theme

Security

• eventlet: Require eventlet >= 0.40.3 (CVE-2021-21419, CVE-2025-58068)
• gevent: Require gevent >= 24.10.1 (CVE-2023-41419, CVE-2024-3219)
• tornado: Require tornado >= 6.5.0 (CVE-2025-47287)

Install

pip install gunicorn==24.0.0

v23.0.0

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Gunicorn 23.0.0 has been released. This version improve HTTP 1.1. support and which improve safety

You're invited to upgrade asap your own installation.

23.0.0 - 2024-08-10

• minor docs fixes (:pr:3217, :pr:3089, :pr:3167)
• worker_class parameter accepts a class (:pr:3079)
• fix deadlock if request terminated during chunked parsing (:pr:2688)
• permit receiving Transfer-Encodings: compress, deflate, gzip (:pr:3261)
• permit Transfer-Encoding headers specifying multiple encodings. note: no parameters, still (:pr:3261)
• sdist generation now explicitly excludes sphinx build folder (:pr:3257)
• decode bytes-typed status (as can be passed by gevent) as utf-8 instead of raising TypeError (:pr:2336)
• raise correct Exception when encounting invalid chunked requests (:pr:3258)
• the SCRIPT_NAME and PATH_INFO headers, when received from allowed forwarders, are no longer restricted for containing an underscore (:pr:3192)
• include IPv6 loopback address [::1] in default for :ref:forwarded-allow-ips and :ref:proxy-allow-ips (:pr:3192)

** NOTE **

• The SCRIPT_NAME change mitigates a regression that appeared first in the 22.0.0 release
• Review your :ref:forwarded-allow-ips setting if you are still not seeing the SCRIPT_NAME transmitted
• Review your :ref:forwarder-headers setting if you are missing headers after upgrading from a version prior to 22.0.0

** Breaking changes **

• refuse requests where the uri field is empty (:pr:3255)
• refuse requests with invalid CR/LR/NUL in heade field values (:pr:3253)
• remove temporary --tolerate-dangerous-framing switch from 22.0 (:pr:3260)
• If any of the breaking changes affect you, be aware that now refused requests can post a security problem, especially so in setups involving request pipe-lining and/or proxies.

Fix CVE-2024-1135

v22.0.0: Gunicorn 22.0 has been released

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Gunicorn 22.0.0 has been released. This version fix the numerous security vulnerabilities. You're invited to upgrade asap your own installation.

Changes:

22.0.0 - 2024-04-17
===================

- use `utime` to notify workers liveness
- migrate setup to pyproject.toml
- fix numerous security vulnerabilities in HTTP parser (closing some request smuggling vectors)
- parsing additional requests is no longer attempted past unsupported request framing
- on HTTP versions < 1.1 support for chunked transfer is refused (only used in exploits)
- requests conflicting configured or passed SCRIPT_NAME now produce a verbose error
- Trailer fields are no longer inspected for headers indicating secure scheme
- support Python 3.12

** Breaking changes **

- minimum version is Python 3.7
- the limitations on valid characters in the HTTP method have been bounded to Internet Standards
- requests specifying unsupported transfer coding (order) are refused by default (rare)
- HTTP methods are no longer casefolded by default (IANA method registry contains none affected)
- HTTP methods containing the number sign (#) are no longer accepted by default (rare)
- HTTP versions < 1.0 or >= 2.0 are no longer accepted by default (rare, only HTTP/1.1 is supported)
- HTTP versions consisting of multiple digits or containing a prefix/suffix are no longer accepted
- HTTP header field names Gunicorn cannot safely map to variables are silently dropped, as in other software
- HTTP headers with empty field name are refused by default (no legitimate use cases, used in exploits)
- requests with both Transfer-Encoding and Content-Length are refused by default (such a message might indicate an attempt to perform request smuggling)
- empty transfer codings are no longer permitted (reportedly seen with really old & broken proxies)

** SECURITY **

- fix CVE-2024-1135

1. Documentation is available there: https://docs.gunicorn.org/en/stable/news.html
2. Packages: https://pypi.org/project/gunicorn/

v21.2.0: Gunicorn 21.2.0 has been released

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Gunicorn 21.2.0 has been released. This version fix the issue introduced in the threaded worker.

Changes:

21.2.0 - 2023-07-19
===================
fix thread worker: revert change considering connection as idle .

*** NOTE ***

This is fixing the bad file description error.

1. Documentation is available there: https://docs.gunicorn.org/en/stable/news.html
2. Packages: https://pypi.org/project/gunicorn/

v21.1.0: Gunicorn 21.1.0 has been released

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gunicorn 21.1.0 has been released. This version fix the issue introduced in the threaded worker.

21.1.0 - 2023-07-18

• fix thread worker: fix socket removal from the queuet checkout 21.x

v21.0.1: Gunicorn 21 has been released

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Gunicorn 21 is out with miscellaneous changes. Enjoy!

We made this release major to start our new release cycle. More info will be provided on our discussion forum.

21.0.1 - 2023-07-17

fix documentation build

21.0.0 - 2023-07-17

support python 3.11
fix gevent and eventlet workers
fix threads support (gththread): improve performance and unblock requests
SSL: noaw use SSLContext object
HTTP parser: miscellaneous fixes
remove unecessary setuid calls
fix testing
improve logging
miscellaneous fixes to core engine

Full Changelog: benoitc/gunicorn@21.0.0...21.0.1

v21.0.0

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v20.1.0

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• document WEB_CONCURRENCY is set by, at least, Heroku
• capture peername from accept: Avoid calls to getpeername by capturing the peer name returned by
  accept
• log a warning when a worker was terminated due to a signal
• fix tornado usage with latest versions of Django
• add support for python -m gunicorn
• fix systemd socket activation example
• allows to set wsgi application in configg file using wsgi_app
• document --timeout = 0
• always close a connection when the number of requests exceeds the max requests
• Disable keepalive during graceful shutdown
• kill tasks in the gthread workers during upgrade
• fix latency in gevent worker when accepting new requests
• fix file watcher: handle errors when new worker reboot and ensure the list of files is kept
• document the default name and path of the configuration file
• document how variable impact configuration
• document the $PORT environment variable
• added milliseconds option to request_time in access_log
• added PIP requirements to be used for example
• remove version from the Server header
• fix sendfile: use socket.sendfile instead of os.sendfile
• reloader: use absolute path to prevent empty to prevent0 InotifyError when a file
  is added to the working directory
• Add --print-config option to print the resolved settings at startup.
• remove the --log-dict-config CLI flag because it never had a working format
  (the logconfig_dict setting in configuration files continues to work)

** Breaking changes **

• minimum version is Python 3.5
• remove version from the Server header

** Documentation **

** Others **

• miscellaneous changes in the code base to be a better citizen with Python 3
• remove dead code
• fix documentation generation