CVE-2026-6103 Phar TAR phar_tar_number() Integer Overflow - Archive Entry Injection

What is CVE-2026-6103?

CVE-2026-6103 is a medium-severity vulnerability in Php Php, published on 25 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official 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.

Weakness: CWE-190

Which versions are affected by CVE-2026-6103?

3 open source packages ship an affected version, including libphp, php and php-min. It affects 1 product.

Products include Php Php.

How do I fix CVE-2026-6103?

Upgrade libphp to a fixed version for your release line: 8.2.34, 8.3.35, 8.4.26 or 8.5.11.

Is CVE-2026-6103 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-6103 exists.

Other vulnerabilities in Php Php

• CVE-2012-2688 Integer overflow in n/a Critical 10.0
• CVE-2012-2376 Memory corruption in n/a Critical 10.0
• CVE-2011-3268 Memory corruption in n/a Critical 10.0
• CVE-2009-4143 Other in n/a Critical 10.0
• CVE-2008-5557 Memory corruption in n/a Critical 10.0

All Php Php vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as AZL-104901, BELL-CVE-2026-6103, BIT-libphp-2026-6103, BIT-php-2026-6103, BIT-php-min-2026-6103, CLEANSTART-2026-ZN45327 and 12 more.