CVE-2026-56766— Hydra - Stack Buffer Overflow in NTLM Authentication Handler
Possible ATT&CK Techniques 1AI
T1190 · Exploit Public-Facing ApplicationAffected Version Matrix 2
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| vanhauser-thc | thc-hydra | ≤ 9.7 | affected |
9cc84c20e75f5fef6bb1790bb9ada2afad2204e2 | unaffected |
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I. Basic Information for CVE-2026-56766
Vulnerability Information
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Vulnerability Title
Hydra - Stack Buffer Overflow in NTLM Authentication Handler
Source: NVD (National Vulnerability Database)
Vulnerability Description
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.
Source: NVD (National Vulnerability Database)
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Source: NVD (National Vulnerability Database)
Vulnerability Type
栈缓冲区溢出
Source: NVD (National Vulnerability Database)
Vulnerability Title
vanhauser-thc thc-hydra 缓冲区错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
vanhauser-thc thc-hydra是vanhauser-thc个人开发者开源的一款网络认证破解工具。 vanhauser-thc thc-hydra 9.7及之前版本存在缓冲区错误漏洞，该漏洞源于处理恶意NTLM Type-2挑战时SMTP、POP3、IMAP、NNTP、HTTP、HTTP-Proxy和HTTP-Proxy-Urlenum模块中的NTLM身份验证存在栈缓冲区溢出，恶意服务器可通过发送包含超长域字符串的特制NTLM Type-2挑战，使base64编码响应数据溢出500字节的栈缓
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
| Vendor | Product | Affected Versions | CPE | Subscribe |
|---|---|---|---|---|
| vanhauser-thc | thc-hydra | 0 ~ 9.7 | - |
II. Public POCs for CVE-2026-56766
| # | POC Description | Source Link | Shenlong Link |
|---|
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Patches & Fixes for CVE-2026-56766 (1)
Vendor Advisories for CVE-2026-56766 (1)
IV. Related Vulnerabilities
Same weakness: CWE-121
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V. Comments for CVE-2026-56766
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