--- title: "TYPO3-PSA-2019-011: Possible Insecure Deserialization in Extbase Request Handling" url: "https://news.typo3.com/security/advisory/typo3-psa-2019-011" description: It has been discovered that TYPO3 CMS can be vulnerable to insecure deserialization. image: "https://news.typo3.com/_assets/d1e01514e4c4a5b3147940fa2ec50682/Images/og-image-news.jpg" date: 2026-06-11 modified: 2026-06-11 categories: - "Developer & Technology" - Public Service Announcement --- # TYPO3-PSA-2019-011: Possible Insecure Deserialization in Extbase Request Handling - [Developer & Technology](https://news.typo3.com/article/category/developer-technology) - Security / [Public Service Announcement](https://news.typo3.com/article/category/security/public-service-announcement) TYPO3-PSA-2019-011: Possible Insecure Deserialization in Extbase Request Handling ================================================================================= 17 December 2019 ![A laptop screen displaying a list of security advisories](https://news.typo3.com/typo3temp/assets/_processed_/d/c/csm_security_blog_default_77f8e86036.webp) It has been discovered that TYPO3 CMS can be vulnerable to insecure deserialization. - ![](https://news.typo3.com/typo3temp/assets/t3g/blog/gravatar/b8266fdc667b773926c59081862ab148.jpeg)[Oliver Hader](https://news.typo3.com/article/author/oliver-hader) - **Component Type:** TYPO3 CMS - **Subcomponent:** Extbase Request Handling (ext:extbase) - **Release Date:** December 17, 2019 - **Impact:** Possible Insecure Deserialization - **Affected Versions:** All before 10.0.0 - **Severity:** none - high - **Suggested CVSS:** [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:F/RL:T/RC:C](https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator?vector=AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:F/RL:T/RC:C&version=3.1) ### Problem Description It has been discovered that request handling in Extbase can be vulnerable to insecure deserialization. User submitted payload has to be signed with a corresponding HMAC-SHA1 using the sensitive TYPO3 *encryptionKey* as secret - invalid or unsigned payload is not deserialized. However, since sensitive information could have been leaked by accident (e.g. in repositories or in commonly known and unprotected backup files), there is the possibility that attackers know the private *encryptionKey* and are able to calculate the required HMAC-SHA1 to allow a malicious payload to be deserialized. Requirements for successfully exploiting this vulnerability (all of the following): - rendering at least one Extbase plugin in the frontend - *encryptionKey* has been leaked (from *LocalConfiguration.php* or corresponding *.env* file) ### Solution Update to TYPO3 versions 8.7.30 or 9.5.12 that fix the problem described. **Update April 22nd, 2020** Due to negative side-effects mentioned hardening had to be [reverted in TYPO3 version 10.4.0 and 9.5.16](https://review.typo3.org/q/Id83f38d20ecd482b517c37c4244d871a40ff0a89). The issue described cannot be exploited without knowing the encryption-key. However in case an individual encryption-key has been leaked to the public, this has to be considered as critical incident. ### Credits Thanks to TYPO3 security team member Oliver Hader who analyzed and fixed the issue. ### General Advice Follow the recommendations that are given in the [TYPO3 Security Guide](https://docs.typo3.org/typo3cms/CoreApiReference/Security/Index.html#security-guidelines). Please subscribe to the [typo3-announce](http://lists.typo3.org/cgi-bin/mailman/listinfo/typo3-announce) mailing list. ![](https://news.typo3.com/typo3temp/assets/t3g/blog/gravatar/cc7cba9757f98fbe05023a139119df74.jpeg) About the Author [Oliver Hader](https://news.typo3.com/article/author/oliver-hader) Core Developer at TYPO3 GmbH,Hof, Germany [Website](https://typo3.com)[Twitter](https://twitter.com/ohader)[LinkedIn](https://www.linkedin.com/in/oliverhader/)[Xing](https://www.xing.com/profile/Oliver_Hader) Oliver started to work with TYPO3 in 2005 and was fascinated by the product and its universe. Since 2007 he is member of the TYPO3 Core Team. After going back to university in 2014 for achieving a postgraduate master degree in internet web science, he is now researching on advanced web technology topics in general and for TYPO3 in particular. In his spare time, Oliver loves to go cycling cross-country in the uplands around Hof (Germany) in northern Bavaria - at the region where he's living as well. [More posts by this author](https://news.typo3.com/article/author/oliver-hader)