CVE-2026-5244

Name	CVE-2026-5244
Description	A vulnerability has been found in Cesanta Mongoose up to 7.20. This affects the function mg_tls_recv_cert of the file mongoose.c of the component TLS 1.3 Handler. Such manipulation of the argument pubkey leads to heap-based buffer overflow. The attack may be launched remotely. The exploit has been disclosed to the public and may be used. Upgrading to version 7.21 mitigates this issue. The name of the patch is 0d882f1b43ff2308b7486a56a9d60cd6dba8a3f1. It is advisable to upgrade the affected component. The vendor was contacted early, responded in a very professional manner and quickly released a fixed version of the affected product.
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
mongoose (PTS)	forky, sid	7.21+ds-2	fixed
swupdate (PTS)	bullseye	2020.11-2+deb11u1	vulnerable
	bookworm	2022.12+dfsg-4+deb12u2	vulnerable
	trixie	2024.12.1+dfsg-3+deb13u2	vulnerable
	forky, sid	2025.12+dfsg-10	fixed

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
mongoose	source	(unstable)	(not affected)
swupdate	source	(unstable)	2025.12+dfsg-10

Notes

- mongoose <not-affected> (Fixed before or with initial upload)
[trixie] - swupdate <no-dsa> (Minor issue)
[bookworm] - swupdate <no-dsa> (Minor issue)
[bullseye] - swupdate <postponed> (Minor issue)