tftp-hpa 5.4 before 6.0 contains an out-of-bounds read vulnerability in rewritestring() in tftpd/remap.c that walks heap memory during jump label searches. Unauthenticated remote attackers can send read or write requests whose filename matches a remap jump rule to crash the forked in.tftpd request handler.

A flaw was found in tftp-hpa. When the in.tftpd remap engine processes an inverse remap rule that also aborts with a non-empty custom error message, it can pass invalid match offsets to the genmatchstring() function. This leads to out-of-bounds read/write operations. A remote, unauthenticated attacker can exploit this vulnerability by sending a specially crafted request, causing the daemon to crash and resulting in a denial of service.