AIKIDO-2026-878106
fast-uri is vulnerable to Server-Side Request Forgery (SSRF)
84
High Risk
This Affects:
fast-uriTL;DR
URI authority parsing does not treat a literal backslash as a delimiter, while Node's WHATWG URL normalizes \ to / for special schemes. The same input can therefore yield different hosts in fast-uri versus fetch()/undici, so host allowlists, SSRF filters, or redirect checks based on fast-uri can be bypassed. The fix rejects URIs whose authority contains a literal backslash.
Who does this affect?
You are affected if you are using a version that falls within the vulnerable range and you use fast-uri for host-based policy checks before passing the same URL to Node's URL or fetch() consumers.
Background info
fast-uri is vulnerable to Server-Side Request Forgery (SSRF) in versions 2.3.1 - 2.4.2, 3.0.0 - 3.1.3 and 4.0.0 - 4.1.0.
How to fix this
Upgrade the fast-uri library to the patch version.
Links
GitHub Release
Are You Affected?
Connect your repositories to instantly see whether vulnerable or malicious packages exist in your codebase.
Free. No credit card required.
I consent to receiving marketing communications based on Aikido’s Privacy Policy.
SOC 2Compliant
ISO 27001Compliant