← back
CVE-2026-85091highCWE-787

zlib 1.3.1.2 through 1.3.2 Heap Buffer Overflow via gz_vacate

41Vexday Risk Score

No sign of exploitation. It has a public proof of concept.

ssvc Attendcvss 8.3epss 0.4%
exploitation probability
0.4%top 62% of all CVEs
observed exploitation
nono source reports it
1 public exploit(s)
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:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N
Affected products
zlib · zlib
⚠ Public resources, to assess the exposure of systems you control or are authorized to test. Test only with authorization.