CVE-2026-18508

GNU Tar through 1.35 allows file overwrite via directory traversal in crafted TAR archives, with a certain two-step process. First, the victim must extract an archive containing a ../ symlink to a critical directory. Second, the victim must extract an archive containing a critical file specified via a relative pathname that begins with the symlink name and ends with the critical file's name, bypassing the 'Member name contains ..' protection.

Directory traversal vulnerability in the safer_name_suffix function in GNU tar versions 1.14 through 1.29 may allow remote attackers to bypass an intended protection mechanism and write to arbitrary files due to improper sanitization of the file_name parameter.

GNU tar has a TOCTOU vulnerability in incremental dumpdir 'X' rename handling. A local attacker with write access to a directory being backed up can influence the restore process if they have access to the system where the restore is performed. During restoration, files or directories may be created, renamed, or overwritten outside the intended extraction directory, potentially leading to unauthorized file modification or privilege escalation.

GNU Tar through 1.34 has a one-byte out-of-bounds read resulting in use of uninitialized memory for a conditional jump. The issue occurs in from_header in list.c via a V7 archive where mtime has approximately 11 whitespace characters.

pax_decode_header in sparse.c in GNU Tar before 1.32 had a NULL pointer dereference when parsing certain archives that have malformed extended headers.

GNU Tar through 1.30, when --sparse is used, mishandles file shrinkage during read access, which allows local users to cause a denial of service (infinite read loop in sparse_dump_region in sparse.c) by modifying a file that is supposed to be archived by a different user's process (e.g., a system backup running as root).

The GNU tar command, when used in FTP sessions, may allow an attacker to execute arbitrary commands.