CVE-2026-6103Public exploit

Archive entry injection via wrapped TAR size

Published Sep 25, 2026 · Updated Sep 25, 2026

Integer overflow in the PHP Phar TAR parser allows attackers to inject archive entries into extracted content via crafted TAR files. phar_tar_number() accumulates an 11-digit octal size into uint32_t without an overflow check, so wrapped sizes misalign block skipping and make file data parse as headers. An application must open an untrusted archive with PharData or phar://; injected entries can replace manifest files and be written by extractTo().

CVSS severity4.0
Medium
EPSS probability0.17%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer overflow in the PHP Phar TAR parser allows attackers to inject archive entries into extracted content via crafted TAR files. phar_tar_number() accumulates an 11-digit octal size into uint32_t without an overflow check, so wrapped sizes misalign block skipping and make file data parse as headers. An application must open an untrusted archive with PharData or phar://; injected entries can replace manifest files and be written by extractTo().

The record

CVE
CVE-2026-6103
Published
Sep 25, 2026
Updated
Sep 25, 2026
Vendor
PHP Development Team
Product
PHP
Classifications
T1565.001
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=8.2.* <8.2.34
  2. Affected versionversion=8.3.* <8.3.35
  3. Affected versionversion=8.4.* <8.4.26
  4. Affected versionversion=8.5.* <8.5.11

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

PHP Development Team · PHPversion=8.2.* <8.2.34; version=8.3.* <8.3.35; version=8.4.* <8.4.26; version=8.5.* <8.5.11

Published CVSS scores

4.0GitHub Security AdvisoryCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

T1565.001Stored Data Manipulation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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