CVE-2026-56766

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Source
https://cve.org/CVERecord?id=CVE-2026-56766
Import Source
https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-56766.json
JSON Data
https://api.test.osv.dev/v1/vulns/CVE-2026-56766
Downstream
Published
2026-06-25T18:01:07.362Z
Modified
2026-06-26T04:11:21.338352808Z
Severity
  • 8.6 (High) CVSS_V4 - 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 CVSS Calculator
Summary
Hydra - Stack Buffer Overflow in NTLM Authentication Handler
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.

Database specific 
{
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/56xxx/CVE-2026-56766.json",
    "cwe_ids": [
        "CWE-121"
    ],
    "cna_assigner": "VulnCheck"
}
References

Affected packages

Git / github.com/vanhauser-thc/thc-hydra

Affected ranges

Type
GIT
Repo
https://github.com/vanhauser-thc/thc-hydra
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Last affected
6c11ce2dff19ce81630c12b001d821dcd4d1567c
Database specific 
{
    "source": "AFFECTED_FIELD",
    "extracted_events": [
        {
            "introduced": "0"
        },
        {
            "last_affected": "9.7"
        }
    ]
}

Affected versions

8.*
8.3
8.6
v8.*
v8.2
v8.4
v8.5
v8.8
v8.9.1
v9.*
v9.0
v9.1
v9.2
v9.3
v9.4
v9.5
v9.6
v9.7

Database specific

source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-56766.json"