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: 2026-09-03
Score: 8.3 High
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

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Tracking

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History

Thu, 03 Sep 2026 01:15:00 +0000

Type Values Removed Values Added
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.
Title zlib 1.3.1.2 through 1.3.2 Heap Buffer Overflow via gz_vacate
First Time appeared Zlib
Zlib zlib
Weaknesses CWE-787
CPEs cpe:2.3:a:zlib:zlib:*:*:*:*:*:*:*:*
Vendors & Products Zlib
Zlib zlib
References
Metrics cvssV3_1

{'score': 7.4, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H'}

cvssV4_0

{'score': 8.3, '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'}

Subscriptions

Zlib Zlib
cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-09-03T01:04:44.460Z

Reserved: 2026-09-02T23:53:05.582Z

Link: CVE-2026-85091

cve-icon Vulnrichment

No data.

cve-icon NVD

No data.

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses