The (1) CHAP and (2) MS-CHAP-V2 authentication capabilities in the PPP Access Concentrator (PPPAC) function in Internet Initiative Japan SE…

The (1) CHAP and (2) MS-CHAP-V2 authentication capabilities in the PPP Access Concentrator (PPPAC) function in Internet Initiative Japan SEIL/B1 firmware 1.00 through 2.52 use the same challenge for each authentication attempt, which allows remote attackers to bypass authentication via a replay attack.