GHSA-5qrq-9645-g5g2
Fix: ethyca/fides@67e43b1GHSA-5qrq-9645-g5g2 is a Cross-site Scripting (XSS) vulnerability in ethyca-fides. O3 Security confirms whether GHSA-5qrq-9645-g5g2 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
ethyca-fides has a DOM-based XSS vulnerability in fides.js via fides_description override
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for GHSA-5qrq-9645-g5g2.
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.
Real-World Exposure
ethyca-fidesReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Summary
fides.js is the script that renders Fides's consent banner on customer websites. It lets the embedding page override the banner's description text at runtime via a URL query parameter, a JavaScript global, or a cookie. On sites that have opted into HTML-formatted descriptions, the overridden value is rendered as live HTML without passing through the server-side sanitiser the rendering path was designed to trust.
The result is a DOM-based XSS that any visitor can trigger with a crafted link, no authentication required. The cookie source lets the payload persist, so a single click can plant a payload that fires on every subsequent banner render across all subdomains until cookies are cleared.
Am I affected?
This vulnerability affects Fides Enterprise deployments that use fides.js for consent management, a.k.a. "Janus", and have HTML-formatted banner descriptions enabled (the FIDES_PRIVACY_CENTER__ALLOW_HTML_DESCRIPTION Privacy Center container env var set to true ). Deployments that do not load fides.js, or that leave HTML descriptions off (the default), are not affected. The vulnerable code lives in the open-source ethyca-fides PyPI package, which is why this is published as a GHSA and CVE against Fides OSS, but only Fides Enterprise consent management platform deployments exercise the affected path.
To self-test, visit any page where your site loads the consent banner, replacing <your-site>:
https://<your-site>/?fides_override_language=en&fides_description=<img src=x onerror="alert(`DOM XSS in fides_description. Origin: ${document.domain}`)">
If a browser alert() appears showing the embedding origin when the banner renders, the deployment is affected. If the banner does not auto-open, click the manage privacy preferences link to display it.
If no alert appears, the deployment is not affected via this path.
The fides_override_language=en parameter is required because experience-translation overrides only apply when the override language matches the active locale. Adjust to match the active locale on the target site if en is not it.
Details
The vulnerability is a trust gap between two features that are safe in isolation but unsafe together.
The first feature is the override mechanism. fides.js lets the embedding page replace certain banner fields at runtime by reading them from the URL, a JavaScript global, or a cookie on the page origin. The description text is one of the overrideable fields.
The second feature is HTML-formatted descriptions. When the allowHTMLDescription server-controlled flag is on, the rendering path writes the description into the DOM as live HTML rather than plain text. This mode relies on a server-side sanitiser (nh3) to clean any HTML before it reaches the client, so the rendering sink can trust its input.
Combining the two breaks the assumption. The override mechanism feeds the description directly from a client-controlled source, never reaching the server, so the sanitiser the rendering path was designed to trust never runs. On a deployment that has both features active, an attacker-supplied value travels straight from URL or cookie to the HTML sink and executes as script.
The cookie source compounds the impact. Cookies set by JavaScript on the apex domain are visible to every subdomain on subsequent loads, so a payload delivered via URL can write a fides_description cookie that fires on every later banner render across the entire site, until the cookie is cleared.
Impact
A successful exploit gives the attacker arbitrary JavaScript execution in the embedding site's origin, with the same authority as the site's own scripts. The payload can read and modify any data the page can access, issue requests on behalf of the visitor, and render content that appears to come from the site itself. The actual consequences on a given deployment depend on what the embedding origin holds and what other defences (CSP, cookie flags, origin isolation) are in place.
The cookie-based persistence variant raises the impact ceiling, since a single click can convert into a payload that fires on every subsequent banner render across the apex and all subdomains until the visitor clears their cookies.
Patches
This vulnerability has been patched in Fides OSS version 2.84.5, specifically ethyca/fides-privacy-center:2.84.5 Users are advised to upgrade to this version or later to secure their systems against these threats.
Fides Enterprise (fidesplus) version 2.84.6 contains the same patch.
Workarounds
Set FIDES_PRIVACY_CENTER__ALLOW_HTML_DESCRIPTION=false on the Privacy Center container(s) and redeploy. The XSS sink relies on the flag being on, so turning it off makes fides.js strip HTML from the description before rendering, regardless of which source the value came from.
Severity
This vulnerability has been assigned a severity of HIGH with a CVSS v4 vector of CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N (7.0, High).
The score reflects the worst realistic exploitation path: an attacker who can plant a fides_description cookie on the target origin gets persistent script execution that fires on every visitor's banner render, with no further interaction required. Cookie-write capability is not always available to a remote attacker, and the score accounts for that as a precondition, but when it is available the impact is script execution in the embedding site's origin every time the banner or modal renders.
The more common delivery path (a crafted link the victim clicks) scores 6.3, Medium, with a vector of CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N. Per the FIRST CVSS 4.0 User Guide, library-level vulnerabilities should be scored against the "reasonable worst-case scenario", since the analyst cannot anticipate every deployment context. We publish the higher score on that basis.
The published score is the base severity of the vulnerability itself. Real-world impact on a given deployment can be higher or lower depending on the embedding site's own defences. Sites with HttpOnly session cookies, strict Content-Security-Policy, and authentication flows isolated from the consent experience origin reduce the surface a payload can reach. Sites with permissive CSP, JavaScript-readable session tokens, or same-origin OIDC/social-login flows expose more. Operators should assess the score against their own environment.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | ethyca-fides | ≥ 2.33.0&&< 2.84.5 | 2.84.5 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ethyca-fides. 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 ethyca-fides to 2.84.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-5qrq-9645-g5g2 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-5qrq-9645-g5g2 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-5qrq-9645-g5g2. 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-5qrq-9645-g5g2 in your dependencies?
O3 detects GHSA-5qrq-9645-g5g2 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.