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CVE Vulnerability Details :
CVE-2026-56766
PUBLISHED
More InfoOfficial Page
Assigner-VulnCheck
Assigner Org ID-83251b91-4cc7-4094-a5c7-464a1b83ea10
View Known Exploited Vulnerability (KEV) details
Published At-25 Jun, 2026 | 18:01
Updated At-25 Jun, 2026 | 18:34
Rejected At-
▼CVE Numbering Authority (CNA)
Hydra - Stack Buffer Overflow in NTLM Authentication Handler

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.

Affected Products
Vendor
vanhauser-thc
Product
thc-hydra
Repo
https://github.com/vanhauser-thc/thc-hydra
Default Status
unaffected
Versions
Affected
  • From 0 through 9.7 (custom)
Unaffected
  • 9cc84c20e75f5fef6bb1790bb9ada2afad2204e2 (git)
Problem Types
TypeCWE IDDescription
CWECWE-121Stack-based Buffer Overflow
Type: CWE
CWE ID: CWE-121
Description: Stack-based Buffer Overflow
Metrics
VersionBase scoreBase severityVector
4.08.6HIGH
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
3.18.8HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Version: 4.0
Base score: 8.6
Base severity: HIGH
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
Version: 3.1
Base score: 8.8
Base severity: HIGH
Vector:
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Metrics Other Info
Impacts
CAPEC IDDescription
Solutions
Configurations
Workarounds
Exploits
Credits
finder
Tristan Madani
Timeline
EventDate
Replaced By
Rejected Reason
References
HyperlinkResource
https://github.com/vanhauser-thc/thc-hydra/commit/9cc84c20e75f5fef6bb1790bb9ada2afad2204e2
patch
https://www.vulncheck.com/advisories/hydra-stack-buffer-overflow-in-ntlm-authentication-handler
third-party-advisory
Hyperlink: https://github.com/vanhauser-thc/thc-hydra/commit/9cc84c20e75f5fef6bb1790bb9ada2afad2204e2
Resource:
patch
Hyperlink: https://www.vulncheck.com/advisories/hydra-stack-buffer-overflow-in-ntlm-authentication-handler
Resource:
third-party-advisory
▼Authorized Data Publishers (ADP)
CISA ADP Vulnrichment
Affected Products
Metrics
VersionBase scoreBase severityVector
Metrics Other Info
Impacts
CAPEC IDDescription
Solutions
Configurations
Workarounds
Exploits
Credits
Timeline
EventDate
Replaced By
Rejected Reason
References
HyperlinkResource
Details not found