Overview
About vulnerability
Impact
fast-uri v3.1.1 and earlier decodes percent-encoded authority delimiters (%40 as @, %3A as :) inside the host component and serializes them back as raw characters. This changes the URI structure, turning a hostname into userinfo plus a different host.
For example, http://trusted.com%40evil.com/ normalizes to http://[email protected]/, which reparses as host evil.com with userinfo trusted.com.
Applications that normalize untrusted URLs before host allowlist checks, redirect validation, or outbound request routing can be steered to a different authority than the original URL appeared to contain.
Patches
Upgrade to fast-uri >= 3.1.2.
Workarounds
None. Upgrade to the patched version.
Details
- Affected product:
- Fastify , ajv-compiler , fast-json-stringify , fast-json-stringify-compiler , fast-uri
- Affected packages:
- fast-uri @ 2.4.2 (+8 more)