Deserialization of Untrusted Data Affecting typo3/cms-core package, versions <12.4.41>=13.0.0, <13.4.23>=14.0.0, <14.0.2
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Start learning- Snyk IDSNYK-PHP-TYPO3CMSCORE-14916954
- published15 Jan 2026
- disclosed13 Jan 2026
- creditVitaly Simonovich
Introduced: 13 Jan 2026
CVE-2026-0859 (opens in a new tab)How to fix?
Upgrade typo3/cms-core to version 12.4.41, 13.4.23, 14.0.2 or higher.
Overview
typo3/cms-core is a free open source enterprise content management system.
Affected versions of this package are vulnerable to Deserialization of Untrusted Data due to deserialization of files without any class restrictions. A local attacker can execute arbitrary PHP code by crafting a malicious file in the mail spool directory that is deserialized during processing.
Note: This is only exploitable when $GLOBALS['TYPO3_CONF_VARS']['MAIL']['transport_spool_type'] = 'file' is configured, and the mailer:spool:send command runs.
Details
Serialization is a process of converting an object into a sequence of bytes which can be persisted to a disk or database or can be sent through streams. The reverse process of creating object from sequence of bytes is called deserialization. Serialization is commonly used for communication (sharing objects between multiple hosts) and persistence (store the object state in a file or a database). It is an integral part of popular protocols like Remote Method Invocation (RMI), Java Management Extension (JMX), Java Messaging System (JMS), Action Message Format (AMF), Java Server Faces (JSF) ViewState, etc.
Deserialization of untrusted data (CWE-502) is when the application deserializes untrusted data without sufficiently verifying that the resulting data will be valid, thus allowing the attacker to control the state or the flow of the execution.