CVE-2024-21636 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in view_component. 1 public exploit reference exists, so weaponization risk is real. A fix is available for view_component — see the affected versions and patch details below.
view_component Cross-site Scripting vulnerability
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2024-21636.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2024-21636 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,156 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
view_component💎view_componentReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.
Description
Impact
What kind of vulnerability is it? Who is impacted?
This is an XSS vulnerability that has the potential to impact anyone rendering a component directly from a controller with the view_component gem. Note that only components that define a #call method (i.e. instead of using a sidecar template) are affected. The return value of the #call method is not sanitized and can include user-defined content.
In addition, the return value of the #output_postamble method is not sanitized, which can also lead to XSS issues.
Patches
Has the problem been patched? What versions should users upgrade to?
Versions 3.9.0 has been released and fully mitigates both the #call and the #output_postamble vulnerabilities.
Workarounds
Is there a way for users to fix or remediate the vulnerability without upgrading?
Sanitize the return value of #call, eg:
class MyComponent < ApplicationComponent
def call
html_escape("<div>#{user_input}</div>")
end
end
References
Are there any links users can visit to find out more?
https://github.com/ViewComponent/view_component/pull/1950
For more information
If you have any questions or comments about this advisory:
Open an issue in the github/view_component project.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | view_component | ≥ 3.0.0&&< 3.9.0 | 3.9.0bundle update view_component --conservative |
| 💎RubyGems | view_component | all versions | 2.83.0bundle update view_component --conservative |
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 view_component, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update view_component to 3.9.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-21636 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2024-21636 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2024-21636. 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-2024-21636 in your dependencies?
O3 Security finds CVE-2024-21636 across RubyGems dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.