Description
fast-uri does not validate the complete RFC 3986 grammar for bracketed IPv6 literals, so a malformed literal with invalid trailing text is silently truncated to a different valid IPv6 address with no error reported.
Recommendation
Update the fast-uri package to the latest compatible version. Followings are version details:
Affected version(s): **>= 4.0.0, < 4.1.3 >= 3.0.0, < 3.1.6 >= 2.3.1, < 2.4.5** Patched version(s): **4.1.3 3.1.6 2.4.5**
References
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- fast-uri vulnerable to server-side request forgery via repeated hostname percent-decoding - CVE-2026-75899
- fast-uri vulnerable to host confusion via percent-encoded scheme normalization - CVE-2026-76172
- fast-uri vulnerable to inconsistent host case normalization via percent-encoded octets - CVE-2026-86472
- LangSmith Client SDK Affected by Server-Side Request Forgery via Tracing Header Injection - CVE-2026-25528
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See something that needs correcting? Let us knowUpdated September 02, 2026