Heap Buffer Overflow in zlib Affected by Non-Blocking Operations
CVE-2026-85091
Key Information:
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What is CVE-2026-85091?
The vulnerability in zlib versions 1.3.1.2 to 1.3.2 involves a heap buffer overflow in the gz_vacate() function, specifically when processing non-blocking gzwrite() operations with stale external buffer pointers. An attacker can exploit this flaw by invoking gzprintf() or gzvprintf() after a write stall, which triggers an unchecked memmove() operation that writes beyond the internal input buffer's boundaries. This could lead to memory corruption, potentially allowing an attacker to execute arbitrary code or manipulate sensitive information.
Affected Version(s)
zlib 1.3.1.2 <= 1.3.2
Exploit Proof of Concept (PoC)
PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.
References
CVSS V4
Timeline
- 🟡
Public PoC available
- 👾
Exploit known to exist
Vulnerability published
Vulnerability Reserved