Remote code execution via attribute-count multiplication
Published Jun 28, 2026 · Updated Jun 28, 2026
Heap buffer overflow in libssh2 1.11.1 and earlier allows remote attackers controlling an SSH server to execute code in a connecting client. The libssh2_publickey_list_fetch function multiplies an untrusted 32-bit num_attrs value by the attribute-structure size without bounding the count, so wraparound allocates a four-byte buffer before the parser writes attribute fields past it. Exploitation requires a 32-bit client that invokes the publickey subsystem against a malicious server.
Summary
What happened
Heap buffer overflow in libssh2 1.11.1 and earlier allows remote attackers controlling an SSH server to execute code in a connecting client. The libssh2_publickey_list_fetch function multiplies an untrusted 32-bit num_attrs value by the attribute-structure size without bounding the count, so wraparound allocates a four-byte buffer before the parser writes attribute fields past it. Exploitation requires a 32-bit client that invokes the publickey subsystem against a malicious server.
The record
- CVE
- CVE-2026-58050
- Published
- Jun 28, 2026
- Updated
- Jun 28, 2026
- Vendor
- libssh2
- Product
- libssh2
- Classifications
- CWE-190, T1203
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 28, 2026CVE publishedPublication date reported by the CVE source.
- Jun 28, 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=0 <=1.11.1
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.
Weakness, pattern, technique
Public exploit references
- libssh2 publickey list calc PoCsfunctional · demonstrated
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Technologies
Your stack
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Your stack
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