GHSA-9mg6-x45v-hcfm
HIGHactiveadmin vulnerable to stored persistent cross-site scripting (XSS) in dynamic form legends
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.
Blast Radius
activeadmin💎activeadminReal-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
Users settings their active admin form legends dynamically may be vulnerable to stored XSS, as long as its value can be injected directly by a malicious user.
For example:
- A public web application allows users to create entities with arbitrary names.
- Active Admin is used to administrate these entities through a private backend.
- The form to edit these entities in the private backend has the following shape (note the dynamic
namevalue dependent on an attribute of theresource):
form do |f|
f.inputs name: resource.name do
f.input :name
f.input :description
end
f.actions
end
Then a malicious user could create an entity with a payload that would get executed in the active admin administrator's browser.
Both form blocks with an implicit or explicit name (i.e., both form resource.name or form name: resource.name would suffer from the problem), where the value of the name can be arbitrarily set by non admin users.
Patches
The problem has been fixed in ActiveAdmin 3.2.2 and ActiveAdmin 4.0.0.beta7.
Workarounds
Users can workaround this problem without upgrading by explicitly escaping the form name using an HTML escaping utility. For example:
form do |f|
f.inputs name: ERB::Util.html_escape(resource.name) do
f.input :name
f.input :description
end
f.actions
end
Upgrading is of course recommended though.
References
https://owasp.org/www-community/attacks/xss/#stored-xss-attacks
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | activeadmin | all versions | 3.2.2 |
| 💎RubyGems | activeadmin | ≥ 4.0.0.beta1&&< 4.0.0.beta7 | 4.0.0.beta7 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for activeadmin. 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 activeadmin to 3.2.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-9mg6-x45v-hcfm 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 GHSA-9mg6-x45v-hcfm 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 GHSA-9mg6-x45v-hcfm. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-9mg6-x45v-hcfm in your dependencies?
O3 detects GHSA-9mg6-x45v-hcfm across RubyGems dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.