fast-uri vulnerable to host confusion via skipped IDN canonicalization on scheme-relative references

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

• CISA KEV Not listed.
• EPSS 0.0040, the 34th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

This record came from the full history of the GitHub Advisory Database, published 2 Sept 2026. New records show when each source confirmed them.

Sources

• GitHub Advisory Database: GHSA-5jgf-p345-68v8
• OSV: GHSA-5jgf-p345-68v8
• github.com/fastify/fast-uri/security/advisories/GHSA-5jgf-p345-68v8
• nvd.nist.gov/vuln/detail/CVE-2026-75931
• github.com/fastify/fast-uri/commit/0256bc8d1f28b5d0ac657faf67e2411a189dfcb5
• github.com/fastify/fast-uri/commit/444ecdad447db2cc23c4d422acc6f0daa6fa8eef
• github.com/fastify/fast-uri/commit/4e4ebd8b245f6ca16e448203559eea3e545453a3
• cna.openjsf.org/security-advisories.html
• github.com/fastify/fast-uri
• github.com/fastify/fast-uri/releases/tag/v2.4.5
• github.com/fastify/fast-uri/releases/tag/v3.1.6
• github.com/fastify/fast-uri/releases/tag/v4.1.3

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.