EUVD-2026-48722

libssh2 through 1.11.1, fixed in commit 42e33d8, contains a pre-authentication heap buffer overflow vulnerability that allows a malicious SSH server to corrupt heap metadata in any connecting client by sending a packet with a packetlength smaller than the cipher's block size during Encrypt-then-M...

The vulnerability of the SSH protocol lies in its ability to adjust packet sequence numbers during connection negotiation and delete arbitrary amounts of SSH protocol messages. This allows attackers to bypass integrity checks, disable existing security functions, and gain unauthorized access to protected information.

The vulnerability of the SSH protocol lies in the ability to alter the sequence numbers of packets during the connection negotiation process, thereby eliminating any number of SSH protocol messages. Exploiting this vulnerability allows a malicious actor to bypass integrity checks, disable existin...