{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "9.7"
              }
            ],
            "source": [
              "DESCRIPTION",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6c11ce2dff19ce81630c12b001d821dcd4d1567c"
            },
            {
              "fixed": "9cc84c20e75f5fef6bb1790bb9ada2afad2204e2"
            }
          ],
          "repo": "https://github.com/vanhauser-thc/thc-hydra",
          "type": "GIT"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "VulnCheck",
    "cwe_ids": [
      "CWE-121"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/56xxx/CVE-2026-56766.json"
  },
  "details": "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.",
  "id": "CVE-2026-56766",
  "modified": "2026-07-08T05:37:48.960605100Z",
  "published": "2026-06-25T18:01:07.362Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/56xxx/CVE-2026-56766.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-56766"
    },
    {
      "type": "ADVISORY",
      "url": "https://www.vulncheck.com/advisories/hydra-stack-buffer-overflow-in-ntlm-authentication-handler"
    },
    {
      "type": "FIX",
      "url": "https://github.com/vanhauser-thc/thc-hydra/commit/9cc84c20e75f5fef6bb1790bb9ada2afad2204e2"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/vanhauser-thc/thc-hydra"
    }
  ],
  "schema_version": "1.7.5",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Hydra - Stack Buffer Overflow in NTLM Authentication Handler"
}