CVE-2026-66034

A missing bounds check in the libssh2 publickey subsystem allows malicious SSH servers to trigger a client-side out-of-bounds read, leaking heap pointers that could enable security bypasses, denial of service, or code execution.

This Moderate impact flaw in libssh2 allows a malicious SSH server to trigger an out-of-bounds read on a connecting client. While requiring user interaction to connect to a compromised server and having high attack complexity, successful exploitation could leak heap pointers, potentially aiding in ASLR bypass and leading to arbitrary code execution or denial of service on Red Hat Hardened Images.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

To mitigate this, strictly avoid connecting to untrusted SSH servers and enforce this policy using outbound network firewalls to block unknown IP addresses. For defense-in-depth, utilize OS-level memory protections and service sandboxing to contain any accidental exposure.