CVE-2026-56766 EXPLOIT
8.8
HIGH · CVSS 3.1 · EPSS 2.4% (pctl 84)
Patch early
A public exploit exists.
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.
Scoring
| CVSS | 8.8 (HIGH, v3.1) |
|---|---|
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H |
| EPSS | 2.44% — more likely to be exploited than 84% of all CVEs |
| Weakness | CWE-121 |
| On CISA KEV | no |
| Public exploit | yes |
| Published | 2026-06-25 |
| Last modified | 2026-07-14 |
Public exploits
| Source | Title | Date |
|---|---|---|
| exploit-db | Hydra - Stack Buffer Overflow | 2026-07-07 |
References
→ the Explorer · watch your stack · NVD