Koajs vulnerable to Cross-Site Scripting (XSS) at ctx.redirect() function
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 software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | koa | < 2.16.1, >= 3.0.0-alpha.1, < 3.0.0-alpha.5 | 2.16.1, 3.0.0-alpha.5 |
References
- CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:L- Weakness (CWE)
CWE-79- Platform
- npm
- Package
koa- Disclosed
- 09.04.2025
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-x2rg-q646-7m2v - CC BY 4.0
Vulnerability history: koa
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 5
- First → latest
- 02.2025 02.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 1
- High 1
- Medium 2
- Low 1
Disclosures per year
- 2025: 4
- 2026: 1
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Koajs vulnerable to Cross-Site Scripting (XSS) at ctx.redirect() function this entry
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