CVE-2026-6322 fast-uri vulnerable to host confusion via percent-encoded authority delimiters
Attackers can bypass host allowlists and redirect requests by exploiting percent-encoded authority delimiters in URI normalization.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-6322?
CVE-2026-6322 is a high-severity server-side request forgery vulnerability in fast-uri, published on 5 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
fast-uri normalize() decoded percent-encoded authority delimiters inside the host component and then re-emitted them as raw delimiters during serialization. A host that combined an allowed domain, an encoded at-sign, and a different domain was re-emitted with the at-sign as a raw userinfo separator, changing the URI's authority to the second domain. Applications that normalize untrusted URLs before host allowlist checks, redirect validation, or outbound request routing can be steered to a different authority than the input appeared to specify. Versions <= 3.1.1 are affected. Update to 3.1.2 or later.
Which versions are affected by CVE-2026-6322?
4 open source packages ship an affected version, including fast-uri. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
fast-uri npm | All versions | 2.4.1 |
fast-uri npm | All versions | 2.4.1 |
fast-uri npm | From 3.0.0 | 3.1.2 |
fast-uri npm | From 3.0.0 | 3.1.2 |
Products include Openjsf Fast-Uri.
How do I fix CVE-2026-6322?
Upgrade fast-uri to a fixed version for your release line: 2.4.1 or 3.1.2.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-6322 being exploited?
There is no known exploitation of CVE-2026-6322 in the wild and no public exploit code.
Other vulnerabilities in fast-uri
- CVE-2026-84292 fast-uri vulnerable to authority injection via an unvalidated port in serialize
- CVE-2026-84394 fast-uri vulnerable to host confusion via an unclosed bracket in the URI authority
- CVE-2026-75899 fast-uri vulnerable to server-side request forgery via repeated hostname percent-decoding
- CVE-2026-75931 fast-uri vulnerable to host confusion via skipped IDN canonicalization on scheme-relative references
- CVE-2026-75975 fast-uri vulnerable to server-side request forgery via malformed IPv6 normalization
Sources
Also known as CLEANSTART-2026-CH75169, CLEANSTART-2026-KV71564, DEBIAN-CVE-2026-6322, ECHO-9cc9-e37b-d919, GHSA-v39h-62p7-jpjc, MINI-3295-78cv-8c8c and 33 more.