Protocol · 1 briefs

RADIUS identity CVEs

Blast-RADIUS is a protocol-level Access-Accept forge. MFA that sits behind RADIUS without Message-Authenticator is optional.

How this protocol fails

RADIUS still fronts VPN, Wi-Fi, and a surprising amount of MFA. A chosen-prefix MD5 collision on the Response Authenticator lets an on-path attacker turn Reject into Accept. Vendor patching ran into 2026. This is not a single-product bug. It is every NAS that still speaks RFC 2865 without Message-Authenticator or RadSec.

What security people should do

Require Message-Authenticator on every client and server. Reject packets that omit it.
Move to RadSec (RADIUS over TLS) where the NAS supports it.
Stop sending PAP/CHAP across a network you do not trust.
Inventory MFA products that still front RADIUS. A phishing-resistant factor behind a forgeable Accept is not phishing-resistant.

Glossary What is passwordless?Phishing-resistant MFA All identity CVEs

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CVE-2024-3596critical 9.0
Blast-RADIUS, MD5 collision forges Access-Accept
RADIUS (RFC 2865) · Protocol-wide · 2024-07-09 · Ongoing
A chosen-prefix MD5 collision on the RADIUS Response Authenticator lets a man-in-the-middle forge Access-Accept, bypass MFA, and escalate when CHAP/PAP run without Message-Authenticator. Protocol-wide. Vendors were still shipping patches into 2026.

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