CVE-2026-56766
Hydra - Stack Buffer Overflow in NTLM Authentication Handler
CVSS Score
8.8
EPSS Score
0.0%
EPSS Percentile
0th
Hydra through 9.7, fixed in commit 9cc84c2, contains a stack buffer overflow in NTLM authentication across SMTP, POP3, IMAP, NNTP, HTTP, HTTP-Proxy, and HTTP-Proxy-Urlenum modules when processing malicious NTLM Type-2 challenges. A malicious server can send a crafted NTLM Type-2 challenge with an excessively long domain string, causing base64-encoded response data to overflow a 500-byte stack buffer by 18 to 330 bytes, enabling remote code execution on systems without stack protection.
| CWE | CWE-121 |
| Vendor | vanhauser-thc |
| Product | thc-hydra |
| Published | Jun 25, 2026 |
| Last Updated | Jun 25, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Affected Versions
vanhauser-thc / thc-hydra
0 ≤ 9.7
References
Credits
Tristan Madani