Home / mailings [USN-8459-1] HAProxy vulnerabilities
Posted on 22 June 2026
Ubuntu Security==========================================================================Ubuntu Security Notice USN-8459-1
June 22, 2026
haproxy vulnerabilities
==========================================================================
A security issue affects these releases of Ubuntu and its derivatives:
- Ubuntu 26.04 LTS
- Ubuntu 25.10
- Ubuntu 24.04 LTS
- Ubuntu 22.04 LTS
Summary:
Several security issues were fixed in HAProxy.
Software Description:
- haproxy: fast and reliable load balancing reverse proxy
Details:
It was discovered that HAProxy incorrectly handled the FCGI demultiplexer
record length field. A remote attacker could possibly use this issue to
cause incorrect request routing, response smuggling, or other memory safety
issues. (CVE-2026-55203)
It was discovered that HAProxy failed to validate the return value of the
HPACK dynamic table defragmentation function when memory was exhausted. A
remote attacker could possibly use this issue to cause HAProxy to crash,
resulting in a denial of service. (CVE-2026-55204)
Update instructions:
The problem can be corrected by updating your system to the following
package versions:
Ubuntu 26.04 LTS
haproxy 3.2.9-1ubuntu2.2
Ubuntu 25.10
haproxy 3.0.12-0ubuntu0.25.10.5
Ubuntu 24.04 LTS
haproxy 2.8.16-0ubuntu0.24.04.3
Ubuntu 22.04 LTS
haproxy 2.4.30-0ubuntu0.22.04.2
In general, a standard system update will make all the necessary changes.
References:
https://ubuntu.com/security/notices/USN-8459-1
CVE-2026-55203, CVE-2026-55204
Package Information:
https://launchpad.net/ubuntu/+source/haproxy/3.2.9-1ubuntu2.2
https://launchpad.net/ubuntu/+source/haproxy/3.0.12-0ubuntu0.25.10.5
https://launchpad.net/ubuntu/+source/haproxy/2.8.16-0ubuntu0.24.04.3
https://launchpad.net/ubuntu/+source/haproxy/2.4.30-0ubuntu0.22.04.2
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