PT-2026-52504 · Socat · Socat

Tristan Madani · Published 2026-06-25 · Updated 2026-06-25 · CVE-2026-56123

NVD

CVSS v3.1

8.1

High

Base vector

AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

socat versions 1.8.0.0 through 1.8.1.1 contain a heap-based buffer overflow vulnerability that allows a malicious SOCKS5 proxy server to overwrite adjacent heap memory by exploiting a sign-extension flaw in the DOMAINNAME reply parser. During connection setup, the domain name length byte is read through a signed char field causing a negative bytes to read value that is implicitly converted to size t, resulting in an unbounded heap write into the 262-byte reply buffer with attacker-controlled size and content.

Fix

Heap Based Buffer Overflow

Weakness Enumeration

CWE-122

Related Identifiers

CVE-2026-56123

Affected Products

Socat

References · 3

• https://nvd.nist.gov/vuln/detail/CVE-2026-56123 · Security Note
• http://dest-unreach.org/socat/CHANGES · Patch
• https://vulncheck.com/advisories/socat-heap-buffer-overflow-via-socks5-reply-parser · Note