CVE-2026-110353

Name	CVE-2026-110353
Description	HAProxy 3.2 before 3.4.6 allows a remote unauthenticated attacker to cause a denial of service (worker-thread CPU exhaustion) via a truncated HTTP/2 PING frame. h2c_handle_ping in src/mux_h2.c does not check for a short read, unlike the other H2 frame handlers. Because the incomplete frame cannot be processed, its data is never consumed, and the H2 multiplexer tasklet is repeatedly woken by that pending data without making progress. The CPU spins until timeout http-request closes the connection, and an attacker opening many such connections can sustain high CPU usage.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, 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
haproxy (PTS)	bookworm	2.6.12-1+deb12u3	vulnerable
	bookworm (security)	2.6.12-1+deb12u4	vulnerable
	trixie	3.0.11-1+deb13u3	vulnerable
	trixie (security)	3.0.11-1+deb13u4	vulnerable
	forky, sid	3.2.26-1	fixed

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
haproxy	source	(unstable)	3.2.26-1

Notes

https://git.haproxy.org/?p=haproxy.git;a=commit;h=cec63e95f62a7412484f1134f5aa227e5b7e1466 (v3.5-dev9~)
https://git.haproxy.org/?p=haproxy-3.2.git;a=commit;h=31a657a0ea846a42fa3eac2409de88f0dce9e2af (v3.2.26)
https://git.haproxy.org/?p=haproxy-3.0.git;a=commit;h=e1672c9ca04c81b544a60e316eb2bb4af02381e1 (v3.0.30)
https://git.haproxy.org/?p=haproxy-2.6.git;a=commit;h=f07a3dbd514ac585177792cca1ff0e5008f28b60 (v2.6.35)