CVE-2020-26216 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in typo3fluid/fluid. 2 public exploit references exist, so weaponization risk is real. O3 Security confirms whether CVE-2020-26216 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Cross-Site Scripting through Fluid view helper arguments
Real-World Exposure
typo3fluid/fluid🐘typo3fluid/fluid🐘typo3fluid/fluid🐘typo3fluid/fluid🐘typo3fluid/fluid🐘typo3fluid/fluid🐘typo3fluid/fluidReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
TYPO3 Fluid before versions 2.0.8, 2.1.7, 2.2.4, 2.3.7, 2.4.4, 2.5.11 and 2.6.10 is vulnerable to Cross-Site Scripting. Three XSS vulnerabilities have been detected in Fluid: 1. TagBasedViewHelper allowed XSS through maliciously crafted additionalAttributes arrays by creating keys with attribute-closing quotes followed by HTML. When rendering such attributes, TagBuilder would not escape the keys. 2. ViewHelpers which used the CompileWithContentArgumentAndRenderStatic trait, and which declared escapeOutput = false, would receive the content argument in unescaped format. 3. Subclasses of AbstractConditionViewHelper would receive the then and else arguments in unescaped format. Update to versions 2.0.8, 2.1.7, 2.2.4, 2.3.7, 2.4.4, 2.5.11 or 2.6.10 of this typo3fluid/fluid package that fix the problem described. More details are available in the linked advisory.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | typo3fluid/fluid | ≥ 2.0.0&&< 2.0.8 | 2.0.8 |
| 🐘Packagist | typo3fluid/fluid | ≥ 2.1.0&&< 2.1.7 | 2.1.7 |
| 🐘Packagist | typo3fluid/fluid | ≥ 2.2.0&&< 2.2.4 | 2.2.4 |
| 🐘Packagist | typo3fluid/fluid | ≥ 2.3.0&&< 2.3.7 | 2.3.7 |
| 🐘Packagist | typo3fluid/fluid | ≥ 2.4.0&&< 2.4.4 | 2.4.4 |
| 🐘Packagist | typo3fluid/fluid | ≥ 2.5.0&&< 2.5.11 | 2.5.11 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for typo3fluid/fluid. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update typo3fluid/fluid to 2.0.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-26216 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2020-26216 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2020-26216. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2020-26216 in your dependencies?
O3 detects CVE-2020-26216 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.