CVE-2026-56766

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.

CVSS v3 8.8 HIGH

8.8^/10

CVSS v3 : HIGH

Vector :

Exploitability : 2.8 / Impact : 5.9

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/vanhauser-thc/thc-hydra/commit/9cc84c20e75f5fef6bb1790bb9ada2afad2204e2
https://www.vulncheck.com/advisories/hydra-stack-buffer-overflow-in-ntlm-authentication-handler

Configurations

No configuration.

History

25 Jun 2026, 19:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-06-25 19:16

Updated : 2026-06-25 19:50

NVD link : CVE-2026-56766

Mitre link : CVE-2026-56766

CVE.ORG link : CVE-2026-56766

JSON object : View

Products Affected

No product.

CWE

CWE-121

Stack-based Buffer Overflow

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