CVE-2026-5503

Name	CVE-2026-5503
Description	In TLSX_EchChangeSNI, the ctx->extensions branch set extensions unconditionally even when TLSX_Find returned NULL. This caused TLSX_UseSNI to attach the attacker-controlled publicName to the shared WOLFSSL_CTX when no inner SNI was configured. TLSX_EchRestoreSNI then failed to clean it up because its removal was gated on serverNameX != NULL. The inner ClientHello was sized before the pollution but written after it, causing TLSX_SNI_Write to memcpy 255 bytes past the allocation boundary.
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
wolfssl (PTS)	bullseye	4.6.0+p1-0+deb11u2	vulnerable
	bookworm	5.5.4-2+deb12u2	vulnerable
	trixie	5.7.2-0.1+deb13u1	vulnerable
	forky, sid	5.9.0-0.2	vulnerable

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
wolfssl	source	(unstable)	(unfixed)

Notes

https://github.com/wolfSSL/wolfssl/pull/10102
Fixed by (merge): https://github.com/wolfSSL/wolfssl/commit/32502e9963a1db43fa42bd1e6edaa27fd8168ad9 (v5.9.1-stable)