Phar TAR phar_tar_number() Integer Overflow - Archive Entry Injection

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.

Scores

EPSS (exploitation in 30 days)

0.16% · top 95% of all CVEs (6 Nov 2026)

CISA SSVC

Exploitation: poc · Automatable: no · Technical impact: partial

The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 4.3.

Weakness

• CWE-190 Integer overflow or wraparound (opens in a new tab)All about CWE-190 and its CVEs

Affected products

• PHP Group · PHP

  • affected 8.2.* – < 8.2.34
  • affected 8.3.* – < 8.3.35
  • affected 8.4.* – < 8.4.26
  • affected 8.5.* – < 8.5.11

References (1)

• https://github.com/php/php-src/security/advisories/GHSA-j3wh-g957-2m85 (opens in a new tab)vendor-advisoryexploit

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2026-6103](https://trackcve.app/badge/CVE-2026-6103.svg)](https://trackcve.app/cve/CVE-2026-6103)

Record last updated 25 Sept 2026, 20:41 UTC.