Summary
Problem
It has been discovered that RSS widgets are susceptible to XML external entity processing.
This vulnerability is reasonable, but is theoretical - it was not possible to actually reproduce the vulnerability with current PHP versions of supported and maintained system distributions.
At least with libxml2 version 2.9, the processing of XML external entities is disabled per default - and cannot be exploited. Besides that, a valid backend user account is needed.
Impact
An XML parser processes external entity references in untrusted input, causing the server to fetch internal resources or remote URLs. Typical impact: local file disclosure, server-side request forgery, or denial of service.
CVE-2020-26229 has a CVSS score of 3.7 (Low). The vector is network-reachable, low privileges required, and user interaction required. 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 (10.4.10); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
Update to TYPO3 version 10.4.10 that fixes the problem described.
Frequently Asked Questions
- What is CVE-2020-26229? CVE-2020-26229 is a low-severity XML external entity injection (XXE) vulnerability in typo3/cms-core (composer), affecting versions >= 10.0.0, < 10.4.10. It is fixed in 10.4.10. An XML parser processes external entity references in untrusted input, causing the server to fetch internal resources or remote URLs.
- How severe is CVE-2020-26229? CVE-2020-26229 has a CVSS score of 3.7 (Low). 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.
- Which packages are affected by CVE-2020-26229?
typo3/cms-core(composer) (versions >= 10.0.0, < 10.4.10)typo3/cms(composer) (versions >= 10.0.0, < 10.4.10)
- Is there a fix for CVE-2020-26229? Yes. CVE-2020-26229 is fixed in 10.4.10. Upgrade to this version or later.
- Is CVE-2020-26229 exploitable, and should I be worried? Whether CVE-2020-26229 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
- What actually determines whether CVE-2020-26229 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.
- How do I fix CVE-2020-26229?
- Upgrade
typo3/cms-coreto 10.4.10 or later - Upgrade
typo3/cmsto 10.4.10 or later
- Upgrade