CVE-2021-41114

Meta

• CVSS: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N/E:F/RL:O/RC:C (3.5)

Problem

It has been discovered that TYPO3 CMS is susceptible to host spoofing due to improper validation of the HTTP Host header. TYPO3 uses the HTTP Host header, for example, to generate absolute URLs during the frontend rendering process. Since the host header itself is provided by the client, it can be forged to any value, even in a name-based virtual hosts environment.

This vulnerability is the same as described in TYPO3-CORE-SA-2014-001 (CVE-2014-3941). A regression, introduced during TYPO3 v11 development, led to this situation. The already existing setting $GLOBALS['TYPO3_CONF_VARS']['SYS']['trustedHostsPattern'] (used as an effective mitigation strategy in previous TYPO3 versions) was not evaluated anymore, and reintroduced the vulnerability.

Credits

Thanks to TYPO3 framework merger Benjamin Franzke who reported and fixed the issue.

References

• TYPO3-CORE-SA-2021-015
• CVE-2014-3941 reintroduced in TYPO3 v11.0.0

The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths. Typical impact: varies by context: data corruption, logic bypass, or denial of service.

CVE-2021-41114 has a CVSS score of 4.8 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (11.5.0); upgrading removes the vulnerable code path.

Kodem intelligence

Update your instance to TYPO3 version 11.5.0 which addresses the problem described.

1. What is CVE-2021-41114? CVE-2021-41114 is a medium-severity improper input validation vulnerability in typo3/cms-core (composer), affecting versions >= 11.0.0, < 11.5.0. It is fixed in 11.5.0. The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths.
2. How severe is CVE-2021-41114? CVE-2021-41114 has a CVSS score of 4.8 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which packages are affected by CVE-2021-41114?
   • typo3/cms-core (composer) (versions >= 11.0.0, < 11.5.0)
   • typo3/cms (composer) (versions >= 11.0.0, < 11.5.0)
4. Is there a fix for CVE-2021-41114? Yes. CVE-2021-41114 is fixed in 11.5.0. Upgrade to this version or later.
5. Is CVE-2021-41114 exploitable, and should I be worried? Whether CVE-2021-41114 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2021-41114 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2021-41114?
   • Upgrade typo3/cms-core to 11.5.0 or later
   • Upgrade typo3/cms to 11.5.0 or later