A haproxy security update has been released for Debian GNU/Linux 11 to address a missing header name length checks in the htx_add_header() and htx_add_trailer() functions.

DSA 4968-1: haproxy security update

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Debian Security Advisory DSA-4968-1 security@debian.org
  https://www.debian.org/security/ Salvatore Bonaccorso
September 07, 2021   https://www.debian.org/security/faq
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Package : haproxy
CVE ID : CVE-2021-40346

Ori Hollander reported that missing header name length checks in the
htx_add_header() and htx_add_trailer() functions in HAProxy, a fast and
reliable load balancing reverse proxy, could result in request smuggling
attacks or response splitting attacks.

Additionally this update addresses #993303 introduced in DSA 4960-1
causing HAProxy to fail serving URLs with HTTP/2 containing '//'.

For the stable distribution (bullseye), this problem has been fixed in
version 2.2.9-2+deb11u2.

We recommend that you upgrade your haproxy packages.

For the detailed security status of haproxy please refer to its security
tracker page at:
  https://security-tracker.debian.org/tracker/haproxy

Further information about Debian Security Advisories, how to apply
these updates to your system and frequently asked questions can be
found at:   https://www.debian.org/security/