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

Medium · CVSS 4.3CVE-2026-6103

Phar TAR phar_tar_number() Integer Overflow - Archive Entry Injection

Answer in brief

CVE-2026-6103 records a Medium severity (CVSS 4.3) vulnerability in Phar TAR phar_tar_number() Integer Overflow - Archive Entry Injection. The current sources do not mark it as known exploited. The current feed maps PHP Group/PHP (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 25, 2026Updated Sep 25, 2026Source checked Sep 25, 2026First seen by HOL Sep 25, 2026Material review Sep 25, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 4.3
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 4.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps PHP Group/PHP (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
PHP Group/PHPgeneric	>=8.2.* <8.2.34 \|\| >=8.3.* <8.3.35 \|\| >=8.4.* <8.4.26 \|\| >=8.5.* <8.5.11	8.2.34, 8.3.35, 8.4.26, 8.5.11

Recommended response

Check inventory. Check lockfiles and deployed manifests for PHP Group/PHP.
Review the reported fix. Update PHP Group/PHP to 8.2.34 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 25, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 25, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 25, 2026

Sources and claim methodology

GitHub security advisorygithub.com

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.