CVE-2026-0859 TYPO3 CMS Allows Insecure Deserialization via Mailer File Spool

What is CVE-2026-0859?

CVE-2026-0859 is a medium-severity unsafe deserialization vulnerability in Typo3 Typo3, published on 13 Jan 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

TYPO3's mail‑file spool deserialization flaw lets local users with write access to the spool directory craft a malicious file that is deserialized during the mailer:spool:send command, enabling arbitrary PHP code execution on the web server. This issue affects TYPO3 CMS versions 10.0.0-10.4.54, 11.0.0-11.5.48, 12.0.0-12.4.40, 13.0.0-13.4.22 and 14.0.0-14.0.1.

Weakness: CWE-502

Which versions are affected by CVE-2026-0859?

10 open source packages ship an affected version, including typo3/cms-core. It affects 1 product.

Products include Typo3 Typo3.

How do I fix CVE-2026-0859?

Upgrade typo3/cms-core to a fixed version for your release line: 10.4.55, 11.5.49, 12.4.41 or 13.4.23.

Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.

Is CVE-2026-0859 being exploited?

There is no known exploitation of CVE-2026-0859 in the wild and no public exploit code.

Other vulnerabilities in Typo3 Typo3

• CVE-2009-0258 Indexed Search Engine for TYPO3 Command Execution via Metacharacter Injection Critical 10.0
• CVE-2011-3583 Typo3 SQL injection due to faulty prepared statements Critical 9.8
• CVE-2011-4628 Typo3 Authentication Bypass Critical 9.8
• CVE-2023-24814 Persisted Cross-Site Scripting in Frontend Rendering in typo3 High 8.8
• CVE-2021-41113 Cross-Site-Request-Forgery in Backend URI Handling in Typo3 High 8.8

All Typo3 Typo3 vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-7vp9-x248-9vr9.