CVE-2021-21339

Problem

User session identifiers were stored in cleartext - without processing of additional cryptographic hashing algorithms. This vulnerability cannot be exploited directly and occurs in combination with a chained attack - like for instance SQL injection in any other component of the system.

Credits

Thanks to TYPO3 security team member Oliver Hader who reported this issue and to TYPO3 core & security team members Benni Mack & Oliver Hader who fixed the issue.

References

• TYPO3-CORE-SA-2021-006

CVE-2021-21339 has a CVSS score of 5.9 (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 (6.2.57, 7.6.51, 8.7.40, 10.4.14, 11.1.1, 9.5.25); upgrading removes the vulnerable code path.

Kodem intelligence

Update to TYPO3 versions 6.2.57, 7.6.51, 8.7.40, 9.5.25, 10.4.14, 11.1.1 that fix the problem described.

1. What is CVE-2021-21339? CVE-2021-21339 is a medium-severity security vulnerability in typo3/cms-core (composer), affecting versions >= 6.2.0, <= 6.2.56. It is fixed in 6.2.57, 7.6.51, 8.7.40, 10.4.14, 11.1.1, 9.5.25.
2. How severe is CVE-2021-21339? CVE-2021-21339 has a CVSS score of 5.9 (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-2021-21339?
   • typo3/cms-core (composer) (versions >= 6.2.0, <= 6.2.56)
   • typo3/cms (composer) (versions >= 10.0.0, < 10.4.14)
4. Is there a fix for CVE-2021-21339? Yes. CVE-2021-21339 is fixed in 6.2.57, 7.6.51, 8.7.40, 10.4.14, 11.1.1, 9.5.25. Upgrade to this version or later.
5. Is CVE-2021-21339 exploitable, and should I be worried? Whether CVE-2021-21339 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-2021-21339 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-2021-21339?
   • Upgrade typo3/cms-core to 6.2.57 or later
   • Upgrade typo3/cms-core to 7.6.51 or later
   • Upgrade typo3/cms-core to 8.7.40 or later
   • Upgrade typo3/cms-core to 10.4.14 or later
   • Upgrade typo3/cms-core to 11.1.1 or later
   • Upgrade typo3/cms-core to 9.5.25 or later
   • Upgrade typo3/cms to 10.4.14 or later
   • Upgrade typo3/cms to 11.1.1 or later
   • Upgrade typo3/cms to 9.5.25 or later