{"id":"CVE-2026-56766","aliases":["EUVD-2026-39515","GHSA-3r6x-6cp5-6575","UBUNTU-CVE-2026-56766","openSUSE-SU-2026:11131-1"],"status":"published","title":"Hydra - Stack Buffer Overflow in NTLM Authentication Handler","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.","severity":{"version":"4.0","score":8.6,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.02438,"percentile":0.84424,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":true,"fix_available":true},"cwes":["CWE-121"],"published":"2026-06-25T18:01:07Z","modified":"2026-10-28T11:17:54Z","exploits":[{"source":"exploitdb","id":"EDB-52622","title":"Hydra - Stack Buffer Overflow","type":"remote","platform":"linux","date":"2026-07-07","url":"https://www.exploit-db.com/exploits/52622"}],"fixes":[{"ecosystem":"openSUSE:Tumbleweed","package":"hydra","fixed_in":["9.7+git20.gbccaea1-1.1"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Ubuntu:16.04:LTS","package":"hydra","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["8.1-1","8.1-1build1","8.1-1build2"]},{"source":"osv","ecosystem":"Ubuntu:18.04:LTS","package":"hydra","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["8.6-1","8.6-1build1"]},{"source":"osv","ecosystem":"Ubuntu:20.04:LTS","package":"hydra","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["9.0-1build1"]},{"source":"osv","ecosystem":"Ubuntu:22.04:LTS","package":"hydra","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["9.1-1","9.2-1","9.2-1ubuntu1"]},{"source":"osv","ecosystem":"Ubuntu:24.04:LTS","package":"hydra","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["9.5-1","9.5-1build1","9.5-1build3"]},{"source":"osv","ecosystem":"Ubuntu:25.10","package":"hydra","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["9.5-3build1"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"hydra","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["9.6-3","9.7-1","9.7-1build1","9.7-2"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"hydra","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["9.5-3build1","9.6-3"]},{"source":"osv","ecosystem":"openSUSE:Tumbleweed","package":"hydra","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"9.7+git20.gbccaea1-1.1"}]}]}],"products":[{"vendor":"vanhauser-thc","product":"thc-hydra"}],"references":[{"url":"https://github.com/vanhauser-thc/thc-hydra/commit/9cc84c20e75f5fef6bb1790bb9ada2afad2204e2","tags":["patch","fix"]},{"url":"https://www.vulncheck.com/advisories/hydra-stack-buffer-overflow-in-ntlm-authentication-handler","tags":["third-party-advisory","advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-56766","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-3r6x-6cp5-6575"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/56xxx/CVE-2026-56766.json","tags":["advisory"]},{"url":"https://github.com/vanhauser-thc/thc-hydra","tags":["package"]},{"url":"https://ubuntu.com/security/CVE-2026-56766","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-56766","tags":["report"]},{"url":"","tags":["advisory"]},{"url":"https://www.suse.com/security/cve/CVE-2026-56766","tags":["web"]}],"sources":{"cve":[{"id":"CVE-2026-56766","title":"Hydra - Stack Buffer Overflow in NTLM Authentication Handler","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.","status":"published","published":"2026-06-25T18:01:07.362Z","modified":"2026-07-14T21:34:18.775Z","cvss":[{"version":"4.0","score":8.6,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N","level":"high","assessor":"cna"},{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","level":"high","assessor":"cna"}],"cwes":["CWE-121"],"updated_at":"2026-11-02T13:37:02.780526Z"}],"euvd":[{"id":"EUVD-2026-39515","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.","status":"published","published":"2026-06-25T18:01:07Z","modified":"2026-07-14T21:34:18Z","cvss":[{"version":"4.0","score":8.6,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N","level":"high"}],"updated_at":"2026-11-02T18:19:57.911867Z"}],"ghsa":[{"id":"GHSA-3r6x-6cp5-6575","title":"Hydra through 9.7, fixed in commit 9cc84c2, contains a stack buffer overflow in NTLM...","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.","status":"published","published":"2026-06-25T21:31:29Z","modified":"2026-06-25T21:31:38Z","cvss":[{"version":"4.0","score":8.6,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high"},{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","level":"high"}],"cwes":["CWE-121"],"updated_at":"2026-11-02T15:08:59.328511Z"}],"nvd":[{"id":"CVE-2026-56766","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.","status":"published","published":"2026-06-25T19:16:43.577Z","modified":"2026-10-25T22:10:00.15Z","cvss":[{"version":"4.0","score":8.6,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high","assessor":"secondary"},{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","level":"high","assessor":"secondary"}],"cwes":["CWE-121"],"updated_at":"2026-11-02T14:12:26.045561Z"}],"osv":[{"id":"CVE-2026-56766","title":"Hydra - Stack Buffer Overflow in NTLM Authentication Handler","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.","status":"published","published":"2026-06-25T18:01:07.362Z","modified":"2026-10-28T11:17:54.787449688Z","cvss":[{"version":"4.0","score":8.6,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-121"],"updated_at":"2026-11-02T15:45:11.609219Z"},{"id":"UBUNTU-CVE-2026-56766","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.","status":"published","published":"2026-06-25T19:16:00Z","modified":"2026-10-17T12:59:11.575569523Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","level":"high"},{"version":"4.0","score":8.6,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N","level":"high"}],"updated_at":"2026-11-02T16:56:41.382716Z"},{"id":"openSUSE-SU-2026:11131-1","title":"hydra-9.7+git20.gbccaea1-1.1 on GA media","description":"These are all security issues fixed in the hydra-9.7+git20.gbccaea1-1.1 package on the GA media of openSUSE Tumbleweed.","status":"published","published":"2026-06-27T00:00:00Z","modified":"2026-06-29T09:45:07.020501836Z","updated_at":"2026-11-02T16:58:38.95195Z"}]}}