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CVE-2026-85091 Details

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.

Metrics

CVSS 3.x Severity and Vector Strings:

CNA: [email protected]CVSS-B:7.4 HIGHVector:CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H

References to Advisories, Solutions, and Tools

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URL	Source(s)	Tag(s)
https://gist.github.com/thesmartshadow/e0b9481792afb7c31e86fee1ff084490	[email protected]
https://github.com/madler/zlib	[email protected]
https://github.com/madler/zlib/blob/v1.3.2/gzwrite.c#L393	[email protected]
https://www.vulncheck.com/advisories/zlib-1.3.1.2-through-1.3.2-heap-buffer-overflow-via-gz-vacate	[email protected]

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-787	Out-of-bounds Write	[email protected]

Affected Products

No affected product data is available for this CVE.

Change History

2 change records found show changes

Date	Action	Recorded By
Sep 3, 2026	CVE Modified	CISA-ADP
Sep 3, 2026	New CVE Received	[email protected]