Vulnerability in wolfSSH Client Key Exchange Messages by wolfSSL

CVE-2026-84897

What is CVE-2026-84897?

In wolfSSL's wolfSSH, versions up to 1.5.0, an issue has been identified with server-side handling of Diffie-Hellman group exchange messages. The server fails to authenticate the legitimacy of messages sent by unauthenticated clients, allowing potential attackers to exploit this by sending specific key exchange messages. The vulnerability stems from the inadequate direction check in the IsMessageAllowedServer() function during the key exchange process. This oversight enables an attacker to negotiate a valid key exchange and, subsequently, produce a Diffie-Hellman key pair using the attacker's own parameters without appropriate validation. Consequently, this flaw could compromise the security of encrypted communications. Users should ensure they are running versions that have the corrective measures or disable certain configurations to mitigate this vulnerability.

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