CVE-2025-5351
MediumCVSS 6.5Exploitation Probability (EPSS)
Low risk43th percentile - higher than 43% of all known CVEs
Summary
A double-free vulnerability was found in the key export functionality of libssh. During error handling, a memory structure is freed but not cleared, potentially leading to a double free if another failure occurs. This could cause heap corruption or application instability in low-memory scenarios.
Risk Assessment
The risk for the organization includes potential heap corruption and instability in systems performing key export operations, which may lead to application crashes or data integrity issues.
Recommendation
It is recommended to immediately update libssh to a version containing the fix that eliminates the double-free issue in the key export function.
Other vulnerabilities in libssh
See all- CVE-2015-3146High
Versions of libssh before 0.6.5 have a state validation issue in the handling of SSH_MSG_NEWKEYS and SSH_MSG_KEXDH_REPLY packets, which can lead to system crashes.
- CVE-2026-59851High
Vulnerability in the libssh library on servers with GSSAPIKeyExchange enabled. The gssapi-keyex path does not verify whether the authenticated Kerberos principal is authorized for the requested local user, allowing authenticated clients to log in as arbitrary users.
- CVE-2026-59850Medium
In the libssh library, if data packets are processed after a channel is closed, channel data callbacks can be invoked after the associated data has already been freed, leading to crashes or possible use-after-free conditions.
- CVE-2026-59849Low
A logic error in libssh's automatic certificate-based public key authentication causes libssh clients to loop indefinitely when configured certificates are missing or repeatedly rejected by a server, leading to denial of service.
- CVE-2026-59848Medium
Vulnerability in libssh. A malicious SFTP server can send responses for unknown request IDs, causing unbounded memory growth and client-side denial of service.
- CVE-2026-59847Medium
A flaw in libssh. Incorrect AES-GCM finalization checks in builds using the OpenSSL backend can effectively remove integrity protection, allowing an in-path attacker to modify plaintext on the wire without detection.
- CVE-2026-59846Low
A flaw in libssh: a malicious username expanded through %r in ProxyCommand handling can inject shell metacharacters, exposing environment variables and causing unintended shell behavior.
- CVE-2026-59845Medium
In libssh, when ProxyCommand is used, an unchecked fork() failure can result in storing PID -1. During cleanup, signals may be sent to processes in the caller's process tree, causing local denial of service.
- CVE-2026-59844Medium
A flaw in libssh: a remote authenticated client can issue SFTP_READ requests with an arbitrarily large length, causing the SFTP server to allocate excessive memory and potentially exhaust it.
- CVE-2026-59843Medium
A flaw in libssh: a remote authenticated peer can advertise a zero maximum packet size in SSH_MSG_CHANNEL_OPEN, causing infinite channel write loops and CPU exhaustion.
Original NVD description (English source)
A flaw was found in the key export functionality of libssh. The issue occurs in the internal function responsible for converting cryptographic keys into serialized formats. During error handling, a memory structure is freed but not cleared, leading to a potential double free issue if an additional failure occurs later in the function. This condition may result in heap corruption or application instability in low-memory scenarios, posing a risk to system reliability where key export operations are performed.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS