Next.js: Server-Side Request Forgery in rewrites via attacker-controlled destination hostname
Impact
A rewrites() or redirects() rule that builds its external destination hostname from request-controlled input can be pointed at an arbitrary hostname, regardless of the rule's hostname suffix. For a rewrite, Next.js proxies the request to that arbitrary host and serves the response from the application's origin, leading to Server-Side Request forgery. A redirects() rule configured this way is vulnerable to an Open Redirect.
This affects any destination that puts a dynamic segment in the hostname, whether from the path:
// next.config.js
module.exports = {
async rewrites() {
return [
{
source: '/:tenant',
destination: 'https://:tenant.api.example.com',
},
]
},
}
or from a has capture:
// next.config.js
module.exports = {
async rewrites() {
return [
{
source: '/',
has: [{ type: 'query', key: 'region', value: '(?<region>.+)' }],
destination: 'https://:region.api.example.com',
},
]
},
}
Workarounds
If you cannot upgrade immediately, do not build the hostname of an external rewrites() or redirects() destination from user-controlled input. If a dynamic subdomain is required, constrain the value to hostname-safe characters: value: '(?<region>[a-z0-9-]+)'.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | next | >= 12.0.0, < 15.5.21, >= 16.0.0, < 16.2.11 | 15.5.21, 16.2.11 |
References
- https://github.com/vercel/next.js/security/advisories/GHSA-p9j2-gv94-2wf4
- https://github.com/vercel/next.js/commit/35f501357e9b0fe7c950b0d6aa8fcf5343f707e9
- https://github.com/vercel/next.js/commit/d3033266c6dff23f7be71e19341fe3a8c6e2c599
- https://github.com/vercel/next.js
- https://github.com/vercel/next.js/releases/tag/v15.5.21
- https://github.com/vercel/next.js/releases/tag/v16.2.11
- CVSS vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:L/VA:N/SC:L/SI:L/SA:N- Weakness (CWE)
CWE-918- Platform
- npm
- Package
next- Disclosed
- 22.07.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-p9j2-gv94-2wf4 - CC BY 4.0
Vulnerability history: next
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
- 73
- First → latest
- 12.2017 10.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 5
- High 27
- Medium 32
- Low 9
Disclosures per year
- 2017: 1
- 2018: 2
- 2019: 0
- 2020: 3
- 2021: 3
- 2022: 3
- 2023: 1
- 2024: 6
- 2025: 14
- 2026: 40
-
Next.js: Server-Side Request Forgery in rewrites via attacker-controlled destination hostname this entry
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