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CVE-2026-6103GHSA-j3wh-g957-2m85

PHP: Phar TAR phar_tar_number() Integer Overflow - Archive Entry Injection

PHP Group PHPRuntimes & languages
Open in ThreatlineRecord JSON
CVSS
4.3Medium
ExploitationPublic exploit codeCISA's assessment says proof of concept code is public, assessed 25 Sep 2026. Not in the KEV catalogCISA via CVE List
Exploit odds (EPSS)0.17%Chance of exploitation activity in the next 30 days, higher than 5% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in8.2.34Also 8.3.35, 8.4.26 and 1 moreCVE List
Published25 Sep 2026Updated 25 Sep 2026CVE List

What fixes it

Show all 8 fixed versions

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

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.

Text from CVE List

Affected versions 8

  • PHPaffected: 8.2.* before 8.2.34CVE List
  • PHPaffected: 8.3.* before 8.3.35CVE List
  • PHPaffected: 8.4.* before 8.4.26CVE List
  • PHPaffected: 8.5.* before 8.5.11CVE List
  • ext-phar, php<8.2.34GitHub
  • ext-phar, php<8.3.35GitHub
  • ext-phar, php<8.4.26GitHub
  • ext-phar, php<8.5.11GitHub

References 1