CVE-2026-85091

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.

CVSS v3 7.4 HIGH

7.4^/10

CVSS v3 : HIGH

Vector :

Exploitability : 2.2 / Impact : 5.2

Attack Vector NETWORK

Attack Complexity HIGH

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://gist.github.com/thesmartshadow/e0b9481792afb7c31e86fee1ff084490
https://github.com/madler/zlib
https://github.com/madler/zlib/blob/v1.3.2/gzwrite.c#L393
https://www.vulncheck.com/advisories/zlib-1.3.1.2-through-1.3.2-heap-buffer-overflow-via-gz-vacate

Configurations

No configuration.

History

No history.

Information

Published : 2026-09-03 13:06

Updated : 2026-09-09 20:41

NVD link : CVE-2026-85091

Mitre link : CVE-2026-85091

CVE.ORG link : CVE-2026-85091

JSON object : View

Products Affected

No product.

CWE

CWE-787

Out-of-bounds Write

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