Heap disclosure or crash via unchecked link length
Published Jun 18, 2026 · Updated Jun 18, 2026
Out-of-bounds read in libssh2 1.11.1 and earlier allows remote attackers to disclose heap data or crash clients via crafted SFTP replies. In sftp_symlink(), the SSH_FXP_NAME parser trusts the packet's link length and copies that many bytes without checking the remaining buffer. Exploitation requires a malicious SSH server or man-in-the-middle position during an SFTP READLINK or REALPATH operation.
Summary
What happened
Out-of-bounds read in libssh2 1.11.1 and earlier allows remote attackers to disclose heap data or crash clients via crafted SFTP replies. In sftp_symlink(), the SSH_FXP_NAME parser trusts the packet's link length and copies that many bytes without checking the remaining buffer. Exploitation requires a malicious SSH server or man-in-the-middle position during an SFTP READLINK or REALPATH operation.
The record
- CVE
- CVE-2025-15661
- Published
- Jun 18, 2026
- Updated
- Jun 18, 2026
- Vendor
- libssh2
- Product
- libssh2
- Classifications
- CWE-125, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 18, 2026CVE publishedPublication date reported by the CVE source.
- Jun 18, 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.
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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