CVE-2026-6103: php_group php Integer Overflow or Wraparound

Vulnerability summary

CVE-2026-6103 is a medium (CVSS 4.3) Integer Overflow or Wraparound vulnerability in php_group php. EPSS estimates a 0.17% chance of exploitation in the next 30 days, higher than 5.5% of scored vulnerabilities.

Timeline

1. 25-09-2026
   PublishedVulnerability first disclosed.
2. 25-09-2026
   Last modifiedVulnerability information updated.

Description

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.

• CWE-190Integer Overflow or WraparoundThe product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.