{"id":"CVE-2026-85091","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-85091","summary":"zlib 1.3.1.2 through 1.3.2 Heap Buffer Overflow via gz_vacate","details":"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.","published":"2026-09-03T01:04:44.460Z","modified":"2026-09-03T11:46:26.141061590Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[],"fix":null,"references":[{"type":"EVIDENCE","url":"https://gist.github.com/thesmartshadow/e0b9481792afb7c31e86fee1ff084490"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/85xxx/CVE-2026-85091.json"},{"type":"PACKAGE","url":"https://github.com/madler/zlib"},{"type":"ARTICLE","url":"https://github.com/madler/zlib/blob/v1.3.2/gzwrite.c#L393"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-85091"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/zlib-1.3.1.2-through-1.3.2-heap-buffer-overflow-via-gz-vacate"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-03T11:46:26.141061590Z"}}