CVE-2026-76844

NameCVE-2026-76844
Descriptionzlib 1.2.11 through 1.3.2 contains a heap buffer overflow: after an underlying write() fails, gz_write() returns without resetting strm.next_in, leaving it pointed at the caller's buffer. A later gz* write call then derives a position from the stale pointer and writes past a heap allocation; any write() failure reaches it, including EPIPE on a blocking descriptor, and in versions before 1.3.1.2 the failed write must be followed by a gzclearerr() call.
SourceCVE (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 Bugs1153063

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
zlib (PTS)bookworm1:1.2.13.dfsg-1vulnerable
trixie1:1.3.dfsg+really1.3.1-1vulnerable
forky1:1.3.dfsg+really1.3.2-3vulnerable
sid1:1.3.dfsg+really1.3.2-4fixed

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

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
zlibsource(unstable)1:1.3.dfsg+really1.3.2-41153063

Notes

Fixed by: https://github.com/madler/zlib/commit/df84af25dc1942490e1d1c899a07619152a46148 (v1.4)
Same fixing change as for CVE-2026-85091

Search for package or bug name: Reporting problems