Heap overwrite via signed SOCKS5 length
Published Jun 25, 2026 · Updated Jun 25, 2026
Heap-based buffer overflow in socat 1.8.0.0 through 1.8.1.1 allows remote attackers to overwrite heap memory via SOCKS5 replies. The DOMAINNAME reply parser reads its length byte through a signed char, producing a negative byte count that converts to an unbounded size_t write into a 262-byte heap buffer. Exploitation requires socat to connect through an attacker-controlled SOCKS5 proxy, and the resulting overwrite can corrupt the socat process or enable code execution.
Summary
What happened
Heap-based buffer overflow in socat 1.8.0.0 through 1.8.1.1 allows remote attackers to overwrite heap memory via SOCKS5 replies. The DOMAINNAME reply parser reads its length byte through a signed char, producing a negative byte count that converts to an unbounded size_t write into a 262-byte heap buffer. Exploitation requires socat to connect through an attacker-controlled SOCKS5 proxy, and the resulting overwrite can corrupt the socat process or enable code execution.
The record
- CVE
- CVE-2026-56123
- Published
- Jun 25, 2026
- Updated
- Jun 25, 2026
- Vendor
- socat
- Product
- socat
- Classifications
- CWE-122, T1203
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 25, 2026CVE publishedPublication date reported by the CVE source.
- Jun 25, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=1.8.0.0 <1.8.1.2
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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