CVE-2020-15098

Meta

• CVSS: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C (8.2)
• CWE-325, CWE-20, CWE-200, CWE-502

Problem

It has been discovered that an internal verification mechanism can be used to generate arbitrary checksums. This allows to inject arbitrary data having a valid cryptographic message authentication code (HMAC-SHA1) and can lead to various attack chains as described below.

• TYPO3-CORE-SA-2020-007, CVE-2020-15099: Potential Privilege Escalation
  • the database server used for a TYPO3 installation must be accessible for an attacker (either via internet or shared hosting network)
  • CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C (7.5, high)
• TYPO3-CORE-SA-2016-013, CVE-2016-5091: Insecure Deserialization & Remote Code Execution
  • an attacker must have access to at least one Extbase plugin or module action in a TYPO3 installation
  • CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C (9.1, critical)

The overall severity of this vulnerability is high (8.2) based on mentioned attack chains and the requirement of having a valid backend user session (authenticated).

Credits

Thanks to TYPO3 security team member Oliver Hader who reported and fixed the issue.

References

• TYPO3-CORE-SA-2020-008

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-2020-15098 has a CVSS score of 8.8 (High). The vector is network-reachable, low 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 (9.5.20, 10.4.6); upgrading removes the vulnerable code path.

Kodem intelligence

Update to TYPO3 versions 9.5.20 or 10.4.6 that fix the problem described.

1. What is CVE-2020-15098? CVE-2020-15098 is a high-severity improper input validation vulnerability in typo3/cms-core (composer), affecting versions >= 9.0.0, < 9.5.20. It is fixed in 9.5.20, 10.4.6. The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths.
2. How severe is CVE-2020-15098? CVE-2020-15098 has a CVSS score of 8.8 (High). 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-2020-15098?
   • typo3/cms-core (composer) (versions >= 9.0.0, < 9.5.20)
   • typo3/cms (composer) (versions >= 10.0.0, < 10.4.6)
4. Is there a fix for CVE-2020-15098? Yes. CVE-2020-15098 is fixed in 9.5.20, 10.4.6. Upgrade to this version or later.
5. Is CVE-2020-15098 exploitable, and should I be worried? Whether CVE-2020-15098 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-2020-15098 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-2020-15098?
   • Upgrade typo3/cms-core to 9.5.20 or later
   • Upgrade typo3/cms-core to 10.4.6 or later
   • Upgrade typo3/cms to 10.4.6 or later
   • Upgrade typo3/cms to 9.5.20 or later