Koajs vulnerable to Cross-Site Scripting (XSS) at ctx.redirect() functionGHSA-x2rg-q646-7m2v
MEDIUMFix: koajs/koa@ff25eb4GHSA-x2rg-q646-7m2v is a medium-severity (CVSS 5) Cross-site Scripting (XSS) vulnerability in koa. A fix is available for koa — see the affected versions and patch details below.
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
- 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 GHSA-x2rg-q646-7m2v.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
koanpmDescription
Summary
In koa < 2.16.1 and < 3.0.0-alpha.5, passing untrusted user input to ctx.redirect() even after sanitizing it, may execute javascript code on the user who use the app.
Patches
This issue is patched in 2.16.1 and 3.0.0-alpha.5.
PoC
Coming soon...
Impact
- Redirect user to another phishing site
- Make request to another endpoint of the application based on user's cookie
- Steal user's cookie
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | koa | all versions | 2.16.1npm install koa@2.16.1 |
| 📦npm | koa | ≥ 3.0.0-alpha.1&&< 3.0.0-alpha.5 | 3.0.0-alpha.5npm install koa@3.0.0-alpha.5 |
Affected Products
koakoajsDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for koa, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update koa to 2.16.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-x2rg-q646-7m2v is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.Source: Red Hat security advisory for GHSA-x2rg-q646-7m2v (CC BY 4.0)
Frequently Asked Questions
Is GHSA-x2rg-q646-7m2v in your dependencies?
Find it across npm, including transitive dependencies.