CVE-2026-6103

phar_tar_number() parses the octal size field of a TAR header into a uint32_t with no overflow check. The field is 11 octal digits wide and holds values up to 0x1FFFFFFFF, so a size above 0xFFFFFFFF silently wraps. The parser then skips the wrong number of data blocks and interprets attacker-controlled file content as the next TAR header, which lets a crafted archive inject entries that PharData reports and extracts as if they were genuine.

• https://github.com/php/php-src/security/advisories/GHSA-j3wh-g957-2m85
• https://github.com/php/php-src/security/advisories/GHSA-j3wh-g957-2m85