HAProxy known bugs for maintenance branch 3.3 : 1

This is maintenance branch 3.3 whose latest version is 3.3.4. If your version is not the last one in the maintenance branch, you are missing fixes for known bugs, and by not updating you are needlessly taking the responsibility for the risk of unexpected service outages and exposing your web site to possible security issues.

The HAProxy development team takes a great care of maintaining stable versions so that all users can apply bug fixes without having to take the risk of upgrading to a new branch. In turn users are expected to apply the fixes when the development team estimates that they were worth being backported to stable branches. In short, if you are running any 3.3 version other than 3.3.4, you're running with known bugs.

Quick links

full changelog for 3.3 : here
browse history for 3.3 : here

Versions available in this branch

This branch contains the following releases :

Date Version Comment

2026-02-19 3.3.4 ⇐ last

2026-02-12 3.3.3

2026-01-29 3.3.2

2025-12-19 3.3.1

2025-11-26 3.3.0

Date	Version	Comment
2026-02-19	3.3.4	⇐ last
2026-02-12	3.3.3
2026-01-29	3.3.2
2025-12-19	3.3.1
2025-11-26	3.3.0

Fixes for known bugs pending in this branch since the last release (3.3.4)

These fixes have already been queued for the next 3.3 release but no version was released with them yet. Note that fixes are backported several at a time from the development branch to maintenance branches, and the absence of a fix here doesn't mean none will be issued soon.

Bugs are almost always tagged with a severity (some people forget the severity tag when the bug is minor). The following severities are used :

MINOR: the bug presents a limited impact and can easily be mitigated ; users rarely upgrade just for these ones ;
MEDIUM: the bug can cause some undesired behaviour and may require some tricky configuration changes to avoid hitting it ; users normally upgrade to get rid of them, or temporarily disable a functionality.
MAJOR: the bug affects short term reliability and cannot easily be worked around without a significant performance penalty or without a significant functional loss ; such bugs don't stay long in the queue without a release and users must plan an upgrade as soon as possible ;
CRITICAL: this one very rarely happens ; it indicates a short-term reliability or security issue for which there is no workaround. A release will be emitted for this fix even if it's alone and users are urged to upgrade immediately. Some distro maintainers might have been informed in advance in order to agree on a coordinated release date.

Total known bugs in the latest version of this branch by category :

Total CRITICAL MAJOR MEDIUM MINOR

1 0 0 1 0

Total	CRITICAL	MAJOR	MEDIUM	MINOR
1	0	0	1	0

Click on the subjects below to get the full description of the bug :

Merge date Subject - Severity (minor, medium, major, critical)

2026-02-26 BUG/MEDIUM: mux-h2: make sure to always report pending errors to the stream

Merge date	Subject - Severity (minor, medium, major, critical)
2026-02-26	BUG/MEDIUM: mux-h2: make sure to always report pending errors to the stream

Known bugs fixed in the development branch after the last commit in this branch

It is important to understand that not all of these commits are necessarily relevant to this version, but clicking on them will show the bug description. All fixes are made first in the development branch and then backported to the maintenance branches. This ensures no fix is lost when upgrading. If a fix was marked for backporting to this branch and is not there yet, it's likely that it is still missing. Do not hesitate to ask on the haproxy mailing list if you feel like a fix has been skipped.

Date	Subject
2026-03-05	BUG/MEDIUM: mux-fcgi: Use a safe loop to resume each stream eligible for sending
2026-03-05	BUG/MAJOR: resolvers: Properly lowered the names found in DNS response
2026-03-05	BUG/MAJOR: fcgi: Fix param decoding by properly checking its size
2026-03-05	BUG/MINOR: http-ana: Increment scf bytes_out value if an haproxy error is sent
2026-03-05	BUG/MINOR: sample: Fix sample to retrieve the number of bytes received and sent
2026-03-05	BUG/MINOR: channel: Increase the stconn bytes_in value in channel_add_input()
2026-03-05	DEBUG: stream: Display the currently running rule in stream dump
2026-03-05	BUG/MINOR: h1-htx: Be sure that H1 response version starts by "HTTP/"
2026-03-05	BUG/MINOR: hlua: Properly enable/disable receives for TCP applets
2026-03-05	BUG/MEDIUM: hlua: Fix end of request detection when retrieving payload
2026-03-05	BUG/MINOR: hlua: Properly enable/disable line receives from HTTP applet
2026-03-05	BUG/MEDIUM: qpack: correctly deal with too large decoded numbers
2026-03-05	BUG/MINOR: quic: fix OOB read in preferred_address transport parameter
2026-03-05	BUG/MINOR: qpack: fix 1-byte OOB read in qpack_decode_fs_pfx()
2026-03-05	BUG/MAJOR: qpack: unchecked length passed to huffman decoder
2026-03-05	BUG/MEDIUM: hpack: correctly deal with too large decoded numbers
2026-03-03	BUG/MEDIUM: stream: Handle TASK_WOKEN_RES as a stream event
2026-03-03	BUG/MINOR: hlua: fix return with push nil on proxy check
2026-02-26	BUG/MINOR: proxy: add dynamic backend into ID tree
2026-02-26	BUG/MINOR: promex: fix server iteration when last server is deleted
2026-02-26	BUG/MINOR: call EXTRA_COUNTERS_FREE() before srv_free_params() in srv_drop()

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