Bug 2494115

Summary: CVE-2026-56766 hydra: Hydra: Remote Code Execution via NTLM Authentication Stack Buffer Overflow [epel-all]
Product: [Fedora] Fedora EPEL Reporter: Srikanth Balasubramanian <sbalasub>
Component: hydraAssignee: Robby Callicotte <rcallicotte>
Status: NEW --- QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: high Docs Contact:
Priority: high    
Version: epel10CC: rcallicotte, rebus
Target Milestone: ---Keywords: Security, SecurityTracking
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Hardware: Unspecified   
OS: Unspecified   
Whiteboard: {"flaws": ["bc77de81-ec49-4b4c-a253-81feacc3dd35"]}
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On:    
Bug Blocks: 2493128    

Description Srikanth Balasubramanian 2026-06-29 09:14:08 UTC 
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

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.