CVE-2026-76844: Zlib

High severity, CVSS 7.4. EPSS: 0.6% chance of exploitation in the next 30 days.

zlib 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.

Affected products

• Zlib Zlib: from 1.2.11, up to and including 1.3.2

Published 2026-08-24. Last modified 2026-10-01.