CVE-2026-6103: PHP Group PHP

Medium severity, CVSS 4.3. EPSS: 0.2% chance of exploitation in the next 30 days.

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.

Affected products

• PHP Group PHP: from 8.2, before 8.2.34 (fixed in 8.2.34); from 8.3, before 8.3.35 (fixed in 8.3.35); from 8.4, before 8.4.26 (fixed in 8.4.26); from 8.5, before 8.5.11 (fixed in 8.5.11)

Published 2026-09-25. Last modified 2026-09-29.