{"cve":{"cve_id":"CVE-2026-85091","is_kev":false,"kev_date_added":null,"kev_vendor_project":null,"kev_product":null,"kev_vulnerability_name":null,"kev_short_description":null,"kev_required_action":null,"kev_due_date":null,"kev_known_ransomware":null,"kev_notes":null,"kev_cwes":null,"epss_score":0.00442,"epss_percentile":0.37443,"epss_as_of":"2026-09-15","description":"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_at":"2026-09-03T01:04:44.460000Z","last_modified_at":"2026-09-09T20:41:07.123000Z","cvss_v3_score":7.4,"cvss_v3_vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H","cvss_v3_severity":"HIGH","cvss_v4_score":8.3,"cvss_v4_vector":"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","cvss_v4_severity":"HIGH","ssvc_decision":null,"ssvc_exploitation":"poc","ssvc_automatable":false,"ssvc_technical_impact":"total","cwes":["CWE-787"],"nvd_references":["https://gist.github.com/thesmartshadow/e0b9481792afb7c31e86fee1ff084490","https://github.com/madler/zlib/blob/v1.3.2/gzwrite.c#L393","https://github.com/madler/zlib","https://www.vulncheck.com/advisories/zlib-1.3.1.2-through-1.3.2-heap-buffer-overflow-via-gz-vacate"],"vuln_status":"Awaiting Analysis","trending_score":null,"is_trending":false,"has_trended":false,"trended_number_one":false,"trending_peak_score":null,"trending_peak_rank":null,"started_trending_at":null,"trended_number_one_at":null,"summary_generated":null,"summary_generated_at":null,"summary_model":null,"created_at":"2026-09-03T01:34:30.376720Z","updated_at":"2026-09-11T23:39:39.689094Z"},"effective_severity":"HIGH","badges":[],"impact_analysis":[],"cvss_v3_decoded":{"version":"3.1","metrics":[{"metric":"AV","name":"Attack Vector","value":"N","value_label":"Network"},{"metric":"AC","name":"Attack Complexity","value":"H","value_label":"High"},{"metric":"PR","name":"Privileges Required","value":"N","value_label":"None"},{"metric":"UI","name":"User Interaction","value":"N","value_label":"None"},{"metric":"S","name":"Scope","value":"U","value_label":"Unchanged"},{"metric":"C","name":"Confidentiality","value":"N","value_label":"None"},{"metric":"I","name":"Integrity","value":"H","value_label":"High"},{"metric":"A","name":"Availability","value":"H","value_label":"High"}]},"cvss_v4_decoded":{"version":"4.0","metrics":[{"metric":"AV","name":"Attack Vector","value":"N","value_label":"Network"},{"metric":"AC","name":"Attack Complexity","value":"H","value_label":"High"},{"metric":"AT","name":"Attack Requirements","value":"N","value_label":"None"},{"metric":"PR","name":"Privileges Required","value":"N","value_label":"None"},{"metric":"UI","name":"User Interaction","value":"N","value_label":"None"},{"metric":"VC","name":"Confidentiality (Vulnerable System)","value":"N","value_label":"None"},{"metric":"VI","name":"Integrity (Vulnerable System)","value":"H","value_label":"High"},{"metric":"VA","name":"Availability (Vulnerable System)","value":"H","value_label":"High"},{"metric":"SC","name":"Confidentiality (Subsequent System)","value":"N","value_label":"None"},{"metric":"SI","name":"Integrity (Subsequent System)","value":"N","value_label":"None"},{"metric":"SA","name":"Availability (Subsequent System)","value":"N","value_label":"None"}]},"affected":[{"vendor_slug":"zlib","vendor_name":"zlib","product_slug":"zlib","product_name":"zlib","version_start":"1.3.1.2","version_start_inclusive":true,"version_end":"1.3.2","version_end_inclusive":true,"cpe23_uri":"cve5:zlib:zlib:1.3.1.2:1.3.2"}],"exploit_refs":[],"news":[],"references":[{"url":"https://gist.github.com/thesmartshadow/e0b9481792afb7c31e86fee1ff084490","source_type":"MISC","tags":[]},{"url":"https://github.com/madler/zlib/blob/v1.3.2/gzwrite.c#L393","source_type":"MISC","tags":[]},{"url":"https://github.com/madler/zlib","source_type":"MISC","tags":[]},{"url":"https://www.vulncheck.com/advisories/zlib-1.3.1.2-through-1.3.2-heap-buffer-overflow-via-gz-vacate","source_type":"VENDOR_ADVISORY","tags":["advisory"]}],"timeline":[{"type":"published","at":"2026-09-03T01:04:44.460000Z","label":"CVE published","source":null},{"type":"ssvc_changed","at":"2026-09-03T14:35:30.387154Z","label":"SSVC decision revised","source":"vulnrichment"},{"type":"ssvc_changed","at":"2026-09-03T14:35:30.387154Z","label":"SSVC decision revised","source":"vulnrichment"},{"type":"ssvc_changed","at":"2026-09-03T14:35:30.387154Z","label":"SSVC decision revised","source":"vulnrichment"}]}