A varnish security update has been released for Debian GNU/Linux 10 LTS to address an issue that may result in a request forgery attack.

DLA 3208-1: varnish security update

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Debian LTS Advisory DLA-3208-1 debian-lts@lists.debian.org
  https://www.debian.org/lts/security/ Markus Koschany
November 27, 2022   https://wiki.debian.org/LTS
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Package : varnish
Version : 6.1.1-1+deb10u4
CVE ID : CVE-2020-11653 CVE-2022-45060
Debian Bug : 956307 1023751

Martin van Kervel Smedshammer discovered a request forgery attack can be
performed on Varnish Cache servers that have the HTTP/2 protocol turned on. An
attacker may introduce characters through the HTTP/2 pseudo-headers that are
invalid in the context of an HTTP/1 request line, causing the Varnish server to
produce invalid HTTP/1 requests to the backend. This may in turn be used to
successfully exploit vulnerabilities in a server behind the Varnish server.

For Debian 10 buster, these problems have been fixed in version
6.1.1-1+deb10u4.

We recommend that you upgrade your varnish packages.

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

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