CVE-2026-6103
Phar TAR phar_tar_number() Integer Overflow - Archive Entry Injection
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.
INFO
Published Date :
Sept. 25, 2026, 9:17 p.m.
Last Modified :
Oct. 23, 2026, 2:07 p.m.
Remotely Exploit :
No
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | dd77f84a-d19a-4638-8c3d-a322d820ed2b | ||||
| CVSS 3.1 | MEDIUM | MITRE-CVE | ||||
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 3.1 | LOW | [email protected] |
Solution
- Validate TAR header size fields for overflow.
- Update parsing logic to check size limits.
- Re-parse archives with the fix.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-6103.
| URL | Resource |
|---|---|
| https://github.com/php/php-src/security/advisories/GHSA-j3wh-g957-2m85 | Vendor Advisory Exploit |
| https://github.com/php/php-src/security/advisories/GHSA-j3wh-g957-2m85 | Vendor Advisory Exploit |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-6103 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-6103
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-6103 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-6103 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Oct. 23, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N Added CPE Configuration OR *cpe:2.3:a:php:php:*:*:*:*:*:*:*:* versions from (including) 8.2.0 up to (excluding) 8.2.34 *cpe:2.3:a:php:php:*:*:*:*:*:*:*:* versions from (including) 8.3.0 up to (excluding) 8.3.35 *cpe:2.3:a:php:php:*:*:*:*:*:*:*:* versions from (including) 8.4.0 up to (excluding) 8.4.26 *cpe:2.3:a:php:php:*:*:*:*:*:*:*:* versions from (including) 8.5.0 up to (excluding) 8.5.11 Added Reference Type PHP Group: https://github.com/php/php-src/security/advisories/GHSA-j3wh-g957-2m85 Types: Exploit, Vendor Advisory Added Reference Type CISA-ADP: https://github.com/php/php-src/security/advisories/GHSA-j3wh-g957-2m85 Types: Exploit, Vendor Advisory -
New CVE Received by [email protected]
Sep. 25, 2026
Action Type Old Value New Value Added 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. Added CVSS V3.1 AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N Added CWE CWE-190 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/6xxx/CVE-2026-6103.json">CVE-2026-6103</a> Added Reference https://github.com/php/php-src/security/advisories/GHSA-j3wh-g957-2m85 -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Sep. 25, 2026
Action Type Old Value New Value Added Reference https://github.com/php/php-src/security/advisories/GHSA-j3wh-g957-2m85 Added SSVC {'id': 'CVE-2026-6103', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'poc'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-09-25T20:41:05.626504Z'}