MEDIUMUnknown →
zlib versions 1.3.1.2 through 1.3.2 contain a heap buffer overflow vulnerability in the gz_vacate() function when processing non-blocking gzwrite() operations with stale external buffer pointers. Att
zlib versions 1.3.1.2 through 1.3.2 contain a heap buffer overflow vulnerability in the gz_vacate() function when processing non-blocking gzwrite() operations with stale external buffer pointers. Attackers can trigger the overflow by calling gzprintf() or gzvprintf() after a write stall, causing an unchecked memmove() to write beyond the internal input buffer boundary.
Affected packages
- klibc
- rsync
- zlib
- zsync
Exploit signal
- Known exploited (CISA KEV)
- No
- EPSS score
- —
- EPSS percentile
- —
EPSS is the probability a CVE is exploited in the wild; percentile is its rank among all CVEs.
Sources
- https://www.cve.org/CVERecord?id=CVE-2026-85091
- https://gist.github.com/thesmartshadow/e0b9481792afb7c31e86fee1ff084490
- https://github.com/madler/zlib/commit/e3dc0a85b7032e98380dec011bc8f2c2ee0d8fca
- https://github.com/madler/zlib
- https://github.com/madler/zlib/blob/v1.3.2/gzwrite.c#L393
- https://www.vulncheck.com/advisories/zlib-1.3.1.2-through-1.3.2-heap-buffer-overflow-via-gz-vacate
Structured record: https://ubuntu.com/security/CVE-2026-85091
Recommended response stack
Snyk — Scan your dependencies in CI and fix this vulnerability.→Socket — Detect malicious and compromised packages before they ship.→
Some links are affiliate links — HackTribune may earn a commission at no extra cost to you.
Get incidents like this as alerts for your stack.
Join the beta