A flaw in libssh allows a malicious SFTP server to send a malformed "longname" field within an SSH_FXP_NAME message during a file listing operation. The missing null check permits a read beyond allocated heap memory, which can cause the client or server application to crash or exhibit unexpected behavior. This results in a denial of service rather than code execution or data breach.

The vulnerability affects systems that use libssh as provided in Red Hat Enterprise Linux releases 6 through 9, Red Hat Hardened Images, and Red Hat OpenShift Container Platform 4. All versions of libssh bundled with these products are potentially vulnerable; specific libssh version information was not provided in the advisory.

The CVSS score of 3.1 indicates low to moderate risk, and the EPSS score of <1% shows a very low likelihood of exploitation in the wild. The vulnerability is not listed in the CISA KEV catalog. Attackers would need remote access to act as an SFTP server capable of sending the crafted message; from that position they could force the victim’s client or server to crash, leading to denial of service. The impact is confined to the affected host or process and does not grant further privileges.