{"id":"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.","modified":"2026-10-22T10:36:30.831391582Z","published":"2026-09-03T01:04:44.460Z","related":["openSUSE-SU-2026:12206-1"],"database_specific":{"cwe_ids":["CWE-787"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/85xxx/CVE-2026-85091.json","cna_assigner":"VulnCheck"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/85xxx/CVE-2026-85091.json"},{"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"},{"type":"PACKAGE","url":"https://github.com/madler/zlib"},{"type":"ARTICLE","url":"https://github.com/madler/zlib/blob/v1.3.2/gzwrite.c#L393"},{"type":"EVIDENCE","url":"https://gist.github.com/thesmartshadow/e0b9481792afb7c31e86fee1ff084490"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/madler/zlib","events":[{"introduced":"570720b0c24f9686c33f35a1b3165c1f568b96be"},{"last_affected":"da607da739fa6047df13e66a2af6b8bec7c2a498"}],"database_specific":{"extracted_events":[{"strategy":"StandardRange","range":[{"introduced":"1.3.1.2"},{"last_affected":"1.3.2"}],"source":"AFFECTED_FIELD"},{"source":"DESCRIPTION","range":[{"introduced":"1.3.1.2"},{"last_affected":"1.3.2"}]}]}}],"versions":["v1.3.2","v1.3.1.2"],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-85091.json"}}],"schema_version":"1.9.2","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N"}]}