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CVE-2026-0859 — Vulnerability in typo3/cms-core — CVE Details

MEDIUM

TYPO3 CMS Allows Insecure Deserialization via Mailer File Spool

Published January 13, 2026Updated February 3, 2026Source: osv

Summary

### Problem Local platform users who can write to TYPO3’s mail‑file spool directory can craft a file that the system will automatically deserialize without any class restrictions. This flaw allows an attacker to inject and execute arbitrary PHP code in the public scope of the web server. The vulnerability is triggered when TYPO3 is configured with `$GLOBALS['TYPO3_CONF_VARS']['MAIL']['transport_spool_type'] = 'file';` and a scheduler task or cron job runs the command `mailer:spool:send`. The spool‑send operation performs the insecure deserialization that is at the core of this issue. ### Solution Update to TYPO3 versions 10.4.55 ELTS, 11.5.49 ELTS, 12.4.41 LTS, 13.4.23 LTS, 14.0.2 that fix the problem described. ### Credits Thanks to Vitaly Simonovich for reporting this issue, and to TYPO3 security team members Elias Häußler and Oliver Hader for fixing it. ### References * [TYPO3-CORE-SA-2026-004](https://typo3.org/security/advisory/typo3-core-sa-2026-004)

Advisory Timeline

  • First published January 13, 2026 (272 days ago).
  • Last revised February 3, 2026 — 20 days after initial publication.

Remediation

Upgrade to the fixed version using your package manager.

Composer
Update typo3/cms-core to 13.4.23 or later
composer require "typo3/cms-core:^13.4.23"
Composer
Update typo3/cms-core to 12.4.41 or later
composer require "typo3/cms-core:^12.4.41"
Composer
Update typo3/cms-core to 10.4.55 or later
composer require "typo3/cms-core:^10.4.55"
Composer
Update typo3/cms-core to 11.5.49 or later
composer require "typo3/cms-core:^11.5.49"
Composer
Update typo3/cms-core to 14.0.2 or later
composer require "typo3/cms-core:^14.0.2"

After upgrading, run your dependency scanner again to confirm the vulnerability is resolved.

Affected Packages (5)

Affects 1 ecosystem: packagist (1).

PackageEcosystemAffectedFixed In
typo3/cms-core
packagist
v13.0.0, v13.0.1, v13.1.0, v13.1.1 (+27 more)13.4.23
typo3/cms-core
packagist
v12.0.0, v12.1.0, v12.1.1, v12.1.2 (+44 more)12.4.41
typo3/cms-core
packagist
v10.0.0, v10.1.0, v10.2.0, v10.2.1 (+39 more)10.4.55
typo3/cms-core
packagist
v11.0.0, v11.1.0, v11.1.1, v11.2.0 (+47 more)11.5.49
typo3/cms-core
packagist
v14.0.0, v14.0.114.0.2

Vulnerability Classification

Common Weakness Enumeration (CWE) identifiers for this vulnerability type.

  • CWE-502
    Deserialization of Untrusted DataMITRE

CVSS Score Breakdown

What the CVSS (Common Vulnerability Scoring System) 8.5 score means for each attack dimension.

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
—
Confidentiality
—
Integrity
—
Availability
—

CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:N/SC:H/SI:H/SA:H

References

Frequently Asked Questions

What is CVE-2026-0859?
TYPO3 CMS Allows Insecure Deserialization via Mailer File Spool This vulnerability has been assigned a severity rating of MEDIUM (CVSS score: 8.5/10).
How do I check if my project is affected by CVE-2026-0859?
CVE-2026-0859 affects typo3/cms-core. Use GeekWala's free vulnerability scanner to check your dependencies against CVE-2026-0859 and 200,000+ other known vulnerabilities.

Severity & Exploitability

CVSS Score
8.5

High exploitability or significant impact. Prioritize remediation within days.

Also Known As

GHSA-7vp9-x248-9vr9

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