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CVE-2026-6103

4.3 · MEDIUM

phar_tar_number() parses the octal size field of a TAR header into a uint32_t with no overflow check.

Published Sep 25, 2026phpCWE-190EPSS 0.16%

Overview

CVE-2026-6103 is a medium-severity vulnerability affecting php php. It was published on September 25, 2026 and has a CVSS 3.1 base score of 4.3 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 4.3, rated MEDIUM. It requires local or adjacent network access to exploit. No authentication or special privileges are required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories and patches from php. Update php to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

Affected products

VendorProductVersionsStatus
phpphp>= 8.2.0, < 8.2.34Affected

References

GitHubgithub.com/php/php-src/security/advisories/GHSA-j3wh-g957-2m85GitHubgithub.com/php/php-src/security/advisories/GHSA-j3wh-g957-2m85

How CyberStrike helps

Frequently asked questions

What is CVE-2026-6103?

CVE-2026-6103 is a medium-severity vulnerability affecting php php. It was published on September 25, 2026 and has a CVSS 3.1 base score of 4.3 (MEDIUM).

How severe is CVE-2026-6103?

This vulnerability has a CVSS 3.1 base score of 4.3, rated MEDIUM. It requires local or adjacent network access to exploit. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-6103?

Check the references section for vendor advisories and patches from php. Update php to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-6103?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-6103 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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