CVE-2026-55738

A stack-based buffer overflow exists in the raw_to_header() function in src/microtar.c in rxi microtar 0.1.0. The function copies the 100-byte name and linkname fields of a TAR header with strcpy() without guaranteeing null termination of the source. The POSIX ustar format permits these fixed-width fields to be fully populated with non-null bytes, so a crafted archive whose linkname field (followed by the trailing padding of the 512-byte raw header) contains no null terminator causes strcpy() to read past the end of the 512-byte raw header stack buffer and to write past the destination header buffer. A remote attacker who supplies a crafted TAR archive that the victim opens or parses (via mtar_open(), mtar_read_header(), or mtar_find()) can cause an out-of-bounds read and a stack buffer overflow, resulting in denial of service (crash) and potentially arbitrary code execution. Confirmed with AddressSanitizer: stack-buffer-overflow READ of size 356 in raw_to_header at src/microtar.c:112.

• https://github.com/rxi/microtar
• https://github.com/rxi/microtar/blob/master/src/microtar.c#L111
• https://raw.githubusercontent.com/rxi/microtar/master/src/microtar.c