7.4highHigh
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.
What the metrics mean
- It is reachable over a network, without needing local access.
- For an attacker who can reach it, exploitation depends on conditions outside the attacker's control.
- To exploit it, no account is needed.
- Beyond that, no action by a user is required.
Scoring
- CVSS
- 7.4 (v3.1)
- Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H- CVSS v4
- 8.3
- Weakness
- CWE-787
- Assigned by
- disclosure@vulncheck.com
Dates
- Published
- 2026-09-03
- Last modified
- 2026-09-09
- Sources
- NVD