Release Date: January 20, 2026Component Type: Third party extension. This extension is not a part of the TYPO3 default installation.Component: "Mailqueue" (mailqueue)Composer Package Name: cpsit/typo3-mailqueueVulnerability Type: Insecure DeserializationAffected Versions: 0.5.0, 0.4.2 and belowSeverity: MediumSuggested CVSS v4.0: AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:N/SC:H/SI:H/SA:HReferences: CVE-2026-0895, CWE-502Problem Description The extension extends TYPO3’s FileSpool component, which was vulnerable to Insecure Deserialization prior to TYPO3-CORE-SA-2026-004. Since the related fix is overwritten by the extension, using the extension with a patched TYPO3 core version still allows for Insecure Deserialization, because the affected vulnerable code was extracted from TYPO3 core to the extension. More information about this vulnerability can be found in the related TYPO3 Core Security Advisory TYPO3-CORE-SA-2026-004. Solution Updated versions 0.5.1 and 0.4.3 are available from the TYPO3 extension manager, packagist and at https://extensions.typo3.org/extension/download/mailqueue/0.4.3/ziphttps://extensions.typo3.org/extension/download/mailqueue/0.5.1/zip Users of the extension are advised to update the extension as soon as possible. Credits Thanks to TYPO3 security team member Elias Häußler for reporting the vulnerability and for providing updated versions of the extension. General Advice Follow the recommendations that are given in the TYPO3 Security Guide. Please subscribe to the typo3-announce mailing list.