CVE-2021-28543

Name	CVE-2021-28543
Description	Varnish varnish-modules before 0.17.1 allows remote attackers to cause a denial of service (daemon restart) in some configurations. This does not affect organizations that only install the Varnish Cache product; however, it is common to install both Varnish Cache and varnish-modules. Specifically, an assertion failure or NULL pointer dereference can be triggered in Varnish Cache through the varnish-modules header.append() and header.copy() functions. For some Varnish Configuration Language (VCL) files, this gives remote clients an opportunity to cause a Varnish Cache restart. A restart reduces overall availability and performance due to an increased number of cache misses, and may cause higher load on backend servers.
Source	CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
varnish-modules (PTS)	bullseye	0.16.0-2.1	fixed
	bookworm	0.20.0-2	fixed
	sid, trixie	0.25.0-1	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
varnish-modules	source	(unstable)	(not affected)

Notes

- varnish-modules <not-affected> (Vulnerable code ot present; bug #985947)
https://varnish-cache.org/security/VSV00006.html
Fixed by: https://github.com/varnish/varnish-modules/commit/2c120e576ebb73bc247790184702ba58dc0afc39 (0.18.0)
Fixed by: https://github.com/varnish/varnish-modules/commit/71a1f1383158cc1c1cb3ab2b4d3ff93b044902f5 (0.17.1)
Introduced by: https://github.com/varnish/varnish-modules/commit/b4d5927a2fbba31b1213225138f8432572414a24 (0.17.0)