CVE-2026-56766

Name of the Vulnerable Software and Affected Versions Hydra versions prior to 9.7 commit 9cc84c2

Description A stack buffer overflow exists in the NTLM authentication process across the SMTP, POP3, IMAP, NNTP, HTTP, HTTP-Proxy, and HTTP-Proxy-Urlenum modules. The issue occurs when the software processes a malicious NTLM Type-2 challenge—a response from a server during the NTLM authentication handshake. A malicious server can send a crafted challenge containing an excessively long domain string, causing the base64-encoded response data to overflow a 500-byte stack buffer by 18 to 330 bytes. This can enable remote code execution on systems that lack stack protection.

Recommendations Update Hydra to the version containing commit 9cc84c2.