CVE-2026-6103

What it is

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.

At a glance

Exploitability

Can be exploited locally on the machine without logging in. Limited direct impact.

Exploit odds

0.2% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-09-25 21:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-23 14:07 UTC Last updatedMost recent change to the record

Details

Published

2026-09-25 21:17 UTC

Last modified

2026-10-23 14:07 UTC

Exploit probability

0.2% · EPSS, next 30 days

Weakness

CWE-190 · Integer overflow

Record status

Analyzed

Affected

• PHP < 8.2.34
• PHP < 8.3.35
• PHP < 8.4.26
• PHP < 8.5.11

Attack profile CVSS 3.1 · 4.3

Attack vector

Local

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Changed

Confidentiality

None

Integrity

Low

Availability

None