CVE-2025-5351 is a medium-severity vulnerability identified in the key export functionality of libssh as implemented in Red Hat Enterprise Linux 10. The flaw arises within an internal function responsible for converting cryptographic keys into serialized formats. Specifically, during error handling, a memory structure is freed but not cleared, which can lead to a double free condition if a subsequent failure occurs later in the function. A double free vulnerability occurs when the same memory location is deallocated more than once, potentially leading to heap corruption. In this case, heap corruption or application instability may manifest, particularly under low-memory conditions when key export operations are performed. Although the vulnerability does not directly impact confidentiality or availability, it poses a risk to system reliability and integrity by potentially causing crashes or unpredictable behavior in applications relying on libssh for cryptographic key management. The CVSS 3.1 base score is 4.2, reflecting a medium severity with network attack vector, high attack complexity, low privileges required, no user interaction, and low impact on confidentiality and integrity, with no impact on availability. No known exploits are currently reported in the wild, and no patches or fixes are explicitly linked in the provided data. The vulnerability is specific to Red Hat Enterprise Linux 10, which integrates libssh for secure shell communications and cryptographic operations.

For European organizations, the impact of this vulnerability primarily concerns system stability and reliability rather than direct data breaches or service outages. Organizations that utilize Red Hat Enterprise Linux 10 in environments where cryptographic key export operations are frequent—such as secure communications, automated key management, or cryptographic services—may experience application crashes or instability under certain error conditions, especially in resource-constrained scenarios. This could disrupt critical services relying on secure shell communications or cryptographic operations, potentially affecting operational continuity. While the vulnerability does not directly allow unauthorized access or data leakage, the resulting instability could be exploited indirectly by attackers to cause denial of service or to facilitate further attacks if combined with other vulnerabilities. European organizations in sectors with stringent uptime and reliability requirements, such as finance, healthcare, and critical infrastructure, should be particularly mindful of this risk. Additionally, organizations with compliance obligations related to system integrity and availability may need to address this vulnerability promptly to maintain regulatory adherence.

To mitigate CVE-2025-5351 effectively, European organizations should: 1) Monitor Red Hat and libssh security advisories closely for official patches or updates addressing this vulnerability and apply them promptly once available. 2) Implement runtime memory protection mechanisms such as Address Space Layout Randomization (ASLR) and heap protection features (e.g., glibc’s malloc debug options or hardened allocators) to reduce the risk of exploitation through heap corruption. 3) Conduct thorough testing of applications and services that perform cryptographic key export operations under low-memory conditions to identify potential instability and implement fallback or error-handling improvements. 4) Limit the exposure of vulnerable systems by restricting network access to trusted hosts and employing strict firewall rules, given the network attack vector. 5) Employ system monitoring and logging to detect anomalous crashes or instability that could indicate exploitation attempts. 6) Where feasible, consider upgrading to later versions of Red Hat Enterprise Linux or alternative distributions not affected by this vulnerability, especially in high-security environments. These steps go beyond generic advice by focusing on proactive monitoring, environment hardening, and targeted testing specific to the nature of this double free vulnerability.