---
id: CVE-2026-6103
title: >-
  phar_tar_number() parses the octal size field of a TAR header into a uint32_t
  with no overflow check
summary: >-
  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 …
severity: medium
cvss: 4.3
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N'
cwe:
  - CWE-190
vendor: PHP Group
product: PHP
affected:
  - PHP >= 8.2.* < 8.2.34
  - PHP >= 8.3.* < 8.3.35
  - PHP >= 8.4.* < 8.4.26
  - PHP >= 8.5.* < 8.5.11
published: '2026-09-25'
updated: '2026-09-25'
sourceUpdated: '2026-09-25T21:17:23.790'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-6103'
references:
  - url: 'https://github.com/php/php-src/security/advisories/GHSA-j3wh-g957-2m85'
    label: security@php.net
  - url: 'https://github.com/php/php-src/security/advisories/GHSA-j3wh-g957-2m85'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-6103.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-6103'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2541638'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-6103'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-6103'
  - url: 'https://access.redhat.com/errata/RHSA-2026:70720'
tags:
  - nvd
  - cve.org
  - exploit-available
  - csaf
  - vex
  - red-hat
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-25T20:41:05.626504Z'
ingestedAt: '2026-09-25T21:19:40.145Z'
patched:
  - hardened_images
---

## Overview

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

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **RHSA-2026:70720** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-09-23 · [advisory](https://access.redhat.com/errata/RHSA-2026:70720)
- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, … · updated 2026-09-25 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-6103.json)