{"id":"CVE-2026-76844","sourceIdentifier":"disclosure@vulncheck.com","published":"2026-08-24T14:17:02.250","lastModified":"2026-10-12T17:10:00.163","vulnStatus":"Deferred","cveTags":[],"descriptions":[{"lang":"en","value":"zlib 1.2.11 through 1.3.2 contains a heap buffer overflow: after an underlying write() fails, gz_write() returns without resetting strm.next_in, leaving it pointed at the caller's buffer. A later gz* write call then derives a position from the stale pointer and writes past a heap allocation; any write() failure reaches it, including EPIPE on a blocking descriptor, and in versions before 1.3.1.2 the failed write must be followed by a gzclearerr() call."},{"lang":"es","value":"zlib 1.2.11 hasta 1.3.2 contiene un desbordamiento de búfer de montón: después de que falle una llamada subyacente a write(), gz_write() retorna sin restablecer strm.next_in, dejándolo apuntando al búfer del llamador. Una llamada posterior de escritura gz entonces deriva una posición a partir del puntero obsoleto y escribe más allá de una asignación de montón; cualquier fallo de write() lo alcanza, incluyendo EPIPE en un descriptor de bloqueo, y en versiones anteriores a la 1.3.1.2 la escritura fallida debe ir seguida de una llamada a gzclearerr()."}],"affected":[{"source":"disclosure@vulncheck.com","affectedData":[{"vendor":"zlib","product":"zlib","defaultStatus":"unaffected","packageURL":"pkg:github/madler/zlib","versions":[{"version":"1.2.11","lessThanOrEqual":"1.3.2","versionType":"custom","status":"affected"}]}]}],"metrics":{"cvssMetricV40":[{"source":"disclosure@vulncheck.com","type":"Secondary","cvssData":{"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","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","exploitMaturity":"NOT_DEFINED","confidentialityRequirement":"NOT_DEFINED","integrityRequirement":"NOT_DEFINED","availabilityRequirement":"NOT_DEFINED","modifiedAttackVector":"NOT_DEFINED","modifiedAttackComplexity":"NOT_DEFINED","modifiedAttackRequirements":"NOT_DEFINED","modifiedPrivilegesRequired":"NOT_DEFINED","modifiedUserInteraction":"NOT_DEFINED","modifiedVulnConfidentialityImpact":"NOT_DEFINED","modifiedVulnIntegrityImpact":"NOT_DEFINED","modifiedVulnAvailabilityImpact":"NOT_DEFINED","modifiedSubConfidentialityImpact":"NOT_DEFINED","modifiedSubIntegrityImpact":"NOT_DEFINED","modifiedSubAvailabilityImpact":"NOT_DEFINED","Safety":"NOT_DEFINED","Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","valueDensity":"NOT_DEFINED","vulnerabilityResponseEffort":"NOT_DEFINED","providerUrgency":"NOT_DEFINED"}}],"cvssMetricV31":[{"source":"disclosure@vulncheck.com","type":"Primary","cvssData":{"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"},"exploitabilityScore":2.2,"impactScore":5.2}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-08-26T18:22:33.313523Z","id":"CVE-2026-76844","options":[{"exploitation":"poc"},{"automatable":"no"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"weaknesses":[{"source":"disclosure@vulncheck.com","type":"Primary","description":[{"lang":"en","value":"CWE-787"}]}],"references":[{"url":"https://gist.github.com/thesmartshadow/e0b9481792afb7c31e86fee1ff084490","source":"disclosure@vulncheck.com"},{"url":"https://github.com/madler/zlib","source":"disclosure@vulncheck.com"},{"url":"https://github.com/madler/zlib/blob/v1.3.2/gzwrite.c#L393","source":"disclosure@vulncheck.com"},{"url":"https://github.com/madler/zlib/commit/df84af25dc1942490e1d1c899a07619152a46148","source":"disclosure@vulncheck.com"},{"url":"https://www.vulncheck.com/advisories/zlib-1.3.1.2-through-1.3.2-heap-buffer-overflow-via-gz-vacate","source":"disclosure@vulncheck.com"}]}