{"id":"CVE-2026-85091","title":"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","summary":"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 cal…","severity":"high","cvss":7.4,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H","cwe":["CWE-787"],"published":"2026-09-03","updated":"2026-09-09","sourceUpdated":"2026-09-09T20:41:07.123","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-85091","references":[{"url":"https://gist.github.com/thesmartshadow/e0b9481792afb7c31e86fee1ff084490","label":"disclosure@vulncheck.com"},{"url":"https://github.com/madler/zlib","label":"disclosure@vulncheck.com"},{"url":"https://github.com/madler/zlib/blob/v1.3.2/gzwrite.c#L393","label":"disclosure@vulncheck.com"},{"url":"https://www.vulncheck.com/advisories/zlib-1.3.1.2-through-1.3.2-heap-buffer-overflow-via-gz-vacate","label":"disclosure@vulncheck.com"}],"tags":["nvd"],"epss":0.00442,"epssPercentile":0.37856,"ingestedAt":"2026-09-09T21:22:45.564Z","slug":"CVE-2026-85091","body":"## Overview\n\nzlib 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":40.7,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}