Changelog¶

24.1.1 - 2026-01-24¶

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)

Official Docker Image: Gunicorn now publishes official Docker images to GitHub Container Registry 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
New --proxy-protocol modes: off, v1, v2, auto
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
Socket Backlog Metric: New gunicorn.socket.backlog gauge metric reports the current socket backlog size on Linux systems
InotifyReloader Enhancement: The inotify-based reloader now watches newly imported modules, not just those loaded at startup

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

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 forwarded-allow-ips and proxy-allow-ips (PR #3192)

Note

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

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.

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

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.md) are refused by default (rare.md)
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.md)
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)