# CVE-2025-5351: libssh double free in key export functionality

Source: https://junglewise.ai/threats/cve-2025-5351-libssh-double-free-in-key-export-functionality  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2025-07-04. Updated: 2026-05-19  
License: CC BY 4.0 with a link back

CVE-2025-5351 · Severity: medium · CVSS 6.5 · Published 2025-07-04

libssh is a widely used library that allows applications to communicate securely using the SSH protocol. A flaw in how the library handles security keys during export could allow an authenticated user to crash an application or cause system instability. This typically occurs in low-memory situations and could lead to a denial of service, affecting the reliability of secure connections and data transfers.

Technologies: [Libssh](https://junglewise.ai/threats/technologies/libssh). Vendors: [Libssh](https://junglewise.ai/threats/vendors/libssh).

## Quick answers

**Is CVE-2025-5351 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2025-5351 being exploited in the wild.

**How severe is CVE-2025-5351?** Medium severity, with a CVSS score of 6.5, published 4 July 2025.

**Which products and versions are affected?** Libssh >= 0.10.0, < 0.11.2.

**Is there a fix for CVE-2025-5351?** A patch was published on 2026-05-19: Red Hat released security updates (RHSA-2026:18683) Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2025-5351 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2025-5351?** Check whether you run Libssh at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A double free vulnerability exists in libssh within the pki_key_to_blob() function, which is responsible for converting cryptographic keys into serialized formats. The flaw occurs during error handling when a memory structure (params) is freed but the pointer is not cleared; if a subsequent failure occurs later in the same function, the structure is freed a second time. This issue specifically affects libssh versions 0.10.0 and later when built against OpenSSL 3.0 or higher. An authenticated attacker can trigger this condition to cause heap corruption or a denial of service (DoS), particularly in low-memory scenarios. The vulnerability has been addressed in libssh version 0.11.2 and various Red Hat Enterprise Linux updates.

## Affected products

- libssh libssh >= 0.10.0, < 0.11.2
- Red Hat Enterprise Linux 6.0, 7.0, 8.0, 9.0, 10.0
- Red Hat Openshift Container Platform 4.0

## Timeline

- 2025-05-30: other: Bug reported to Red Hat Bugzilla
- 2025-07-04: disclosed: CVE published
- 2026-05-19: patched: Red Hat released security updates (RHSA-2026:18683)

## References

- [https://access.redhat.com/errata/RHSA-2026:18683](https://access.redhat.com/errata/RHSA-2026:18683)
- [https://access.redhat.com/security/cve/CVE-2025-5351](https://access.redhat.com/security/cve/CVE-2025-5351)
- [https://bugzilla.redhat.com/show_bug.cgi?id=2369367](https://bugzilla.redhat.com/show_bug.cgi?id=2369367)

## Related threats

- [libssh authentication bypass in GSSAPIKeyExchange](https://junglewise.ai/threats/cve-2026-59851-libssh-authentication-bypass-in-gssapikeyexchange)
- [libssh use-after-free in channel data callbacks](https://junglewise.ai/threats/cve-2026-59850-libssh-use-after-free-in-channel-data-callbacks)
- [libssh infinite loop in certificate-based authentication](https://junglewise.ai/threats/cve-2026-59849-libssh-infinite-loop-in-certificate-based-authentication)
- [libssh denial of service via memory exhaustion in SFTP client](https://junglewise.ai/threats/cve-2026-59848-libssh-denial-of-service-via-memory-exhaustion-in-sftp-client)
- [libssh integrity protection bypass in OpenSSL AES-GCM backend](https://junglewise.ai/threats/cve-2026-59847-libssh-integrity-protection-bypass-in-openssl-aes-gcm-backend)