CVE-2026-32853

Name	CVE-2026-32853
Description	LibVNCServer versions 0.9.15 and prior (fixed in commit 009008e) contain a heap out-of-bounds read vulnerability in the UltraZip encoding handler that allows a malicious VNC server to cause information disclosure or application crash. Attackers can exploit improper bounds checking in the HandleUltraZipBPP() function by manipulating subrectangle header counts to read beyond the allocated heap buffer.
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)
Debian Bugs	1132016

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
libvncserver (PTS)	bullseye	0.9.13+dfsg-2+deb11u1	vulnerable
	bookworm	0.9.14+dfsg-1	vulnerable
	trixie	0.9.15+dfsg-1	vulnerable
	forky, sid	0.9.15+dfsg-3	fixed

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
libvncserver	source	(unstable)	0.9.15+dfsg-3			1132016

Notes

https://github.com/LibVNC/libvncserver/security/advisories/GHSA-87q7-v983-qwcj
Fixed by: https://github.com/LibVNC/libvncserver/commit/009008e2f4d5a54dd71f422070df3af7b3dbc931