CVE-2025-5318 is a vulnerability identified in the libssh library, specifically in versions before 0.11.2. The flaw exists in the sftp_handle function, where an incorrect comparison check allows the function to perform an out-of-bounds read by accessing memory beyond the valid handle list. This results in the function returning an invalid pointer, which is subsequently used in further processing. The consequence is that an authenticated remote attacker can exploit this flaw to read unintended memory regions, potentially exposing sensitive information such as cryptographic keys, credentials, or other confidential data stored in memory. Additionally, the out-of-bounds read can affect the stability and availability of the service, potentially causing crashes or denial of service conditions. The vulnerability requires the attacker to have valid authentication credentials, but no user interaction is needed once authenticated. The CVSS v3.1 base score is 8.1, reflecting a high severity due to the network attack vector, low attack complexity, and significant impact on confidentiality and availability. The vulnerability affects Red Hat Enterprise Linux 10, which bundles libssh versions prior to 0.11.2. No public exploits have been reported yet, but the flaw's nature makes it a critical concern for environments relying on secure file transfer via SSH. The root cause is a logic error in boundary checking within the sftp_handle function, emphasizing the importance of rigorous input validation and memory safety in security-critical libraries like libssh.

For European organizations, the impact of CVE-2025-5318 can be substantial, especially for those relying on Red Hat Enterprise Linux 10 and libssh for secure file transfer operations. Confidentiality is at risk due to the potential exposure of sensitive memory contents, which could include private keys, user credentials, or other critical data. This exposure could facilitate further attacks such as privilege escalation or lateral movement within networks. The availability of services may also be affected if the out-of-bounds read leads to crashes or denial of service, disrupting business operations. Sectors such as finance, healthcare, government, and critical infrastructure that depend heavily on secure SSH communications are particularly vulnerable. The requirement for authentication limits the attack surface but does not eliminate risk, as compromised credentials or insider threats could exploit this vulnerability. Given the widespread use of Red Hat Enterprise Linux in European enterprises and public sector organizations, the vulnerability poses a significant threat to data security and operational continuity.

To mitigate CVE-2025-5318, organizations should immediately upgrade libssh to version 0.11.2 or later, where the vulnerability is patched. If upgrading is not immediately feasible, applying vendor-provided patches or workarounds is critical. Organizations should audit and restrict SFTP access, ensuring that only trusted and authenticated users have permissions to interact with the vulnerable sftp_handle function. Implementing strict credential management and monitoring for unusual authentication attempts can reduce exploitation risk. Network segmentation and the use of intrusion detection systems tuned to detect anomalous SSH or SFTP activity can help identify exploitation attempts early. Additionally, conducting memory integrity checks and service stability monitoring can detect potential crashes or abnormal behavior caused by exploitation. Regular vulnerability scanning and penetration testing focused on SSH services should be incorporated into security programs. Finally, educating administrators about the risks and ensuring timely patch management processes are essential to prevent exploitation.