Bug 2572354

Summary: CVE-2026-127030 freeradius: Stack buffer overflow via unchecked EAP-FAST SessionTicket length [fedora-all]
Product: [Fedora] Fedora Reporter: Vladimir Vasilev <vvasilev>
Component: freeradiusAssignee: Antonio Torres <antorres>
Status: NEW --- QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: high Docs Contact:
Priority: high    
Version: rawhideCC: antorres, lemenkov
Target Milestone: ---Keywords: Security, SecurityTracking
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard: {"flaws": ["48302ac8-d769-45b2-ae63-3fc5b6f305dc"]}
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On:    
Bug Blocks: 2572340    

Description Vladimir Vasilev 2026-11-12 12:22:15 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.

A flaw was found in freeradius's EAP-FAST module. The SessionTicket callback invoked during the TLS ClientHello phase of the EAP-FAST handshake validates the PAC-Opaque length using mismatched integer types, allowing an attacker-supplied value to underflow and bypass the check. The callback then decrypts attacker-controlled ciphertext into a fixed-size buffer before the authentication tag is verified, so a crafted ClientHello can write data past the end of a stack buffer. A remote, unauthenticated client speaking EAP-FAST to a server with the module enabled can trigger this to crash the RADIUS server process before any credential exchange.