{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-85091", "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "state": "PUBLISHED", "assignerShortName": "VulnCheck", "dateReserved": "2026-09-02T23:53:05.582Z", "datePublished": "2026-09-03T01:04:44.460Z", "dateUpdated": "2026-09-03T01:04:44.460Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "shortName": "VulnCheck", "dateUpdated": "2026-09-03T01:04:44.460Z"}, "datePublic": "2026-09-02T00:00:00.000Z", "title": "zlib 1.3.1.2 through 1.3.2 Heap Buffer Overflow via gz_vacate", "descriptions": [{"lang": "en", "value": "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."}], "problemTypes": [{"descriptions": [{"lang": "en", "description": "Out-of-bounds Write", "cweId": "CWE-787", "type": "CWE"}]}], "affected": [{"vendor": "zlib", "product": "zlib", "defaultStatus": "unaffected", "packageURL": "pkg:github/madler/zlib", "versions": [{"version": "1.3.1.2", "lessThanOrEqual": "1.3.2", "status": "affected", "versionType": "custom"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:zlib:zlib:*:*:*:*:*:*:*:*", "versionStartIncluding": "1.3.1.2", "versionEndIncluding": "1.3.2"}]}]}], "metrics": [{"cvssV4_0": {"version": "4.0", "vectorString": "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", "baseScore": 8.3, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "HIGH", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "HIGH", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE"}}, {"cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H", "baseScore": 7.4, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}}], "references": [{"url": "https://gist.github.com/thesmartshadow/e0b9481792afb7c31e86fee1ff084490", "name": "Technical report and proof of concept", "tags": ["technical-description", "exploit"]}, {"url": "https://github.com/madler/zlib/blob/v1.3.2/gzwrite.c#L393", "tags": ["technical-description"]}, {"url": "https://github.com/madler/zlib", "tags": ["product"]}, {"name": "VulnCheck Advisory: zlib 1.3.1.2 through 1.3.2 Heap Buffer Overflow via gz_vacate", "tags": ["third-party-advisory"], "url": "https://www.vulncheck.com/advisories/zlib-1.3.1.2-through-1.3.2-heap-buffer-overflow-via-gz-vacate"}], "credits": [{"lang": "en", "value": "Ali Firas (thesmartshadow)", "type": "finder"}], "x_generator": {"engine": "vulncheck-endgame"}}}}

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{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "[1.3.1.2,1.3.2]"}}], "enrichment": {"confidence": 95.0, "confidence_source": "inferred", "scores": [{"score": 95.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "zlib", "source": "cna", "vendor": "zlib"}, "product": "zlib", "vendor": "zlib"}], "created": "2026-09-03T09:30:08.122748+00:00", "updated": "2026-09-03T10:30:12.261872+00:00", "vendors": ["zlib", "zlib$PRODUCT$zlib"]}