CVE-2026-75975: Fast uri Fast-uri Vulnerable To Server-side Request Vulnerability
HIGHCVE-2026-75975 is a HIGH (CVSS 7.5) fast-uri vulnerable to server-side request vulnerability (CWE-20: Improper Input Validation) affecting Fast uri libraries in the npm ecosystem. The issue involves fast-uri vulnerable to server-side request forgery via malformed ipv6 normalization. Remediation is available by upgrading affected packages to version 2.4.5, 3.1.6, 4.1.3.
CVE-2026-75975 at a Glance
Security Impact
CVSS: 7.5
The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N).
How to Fix CVE-2026-75975
To remediate this vulnerability, upgrade all affected Fast uri dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
npm install fast-uri@2.4.5npm install fast-uri@3.1.6npm install fast-uri@4.1.3Run the following command in your project directory to verify that all resolved dependencies use the patched release:
npm ls fast-uriHow to Check if You Are Affected
To determine whether your Node.js application is affected by CVE-2026-75975, inspect your project dependencies using npm:
npm ls fast-uriAnalyze the terminal output to locate any version of Fast uri in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.4.5), your application is affected.
Note: The npm ls fast-uri command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-20: Improper Input Validation, where the product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. In Fast uri, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
CVE-2026-75975 Affected Fast uri Versions
3 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
fast-uri
|
npm |
≥ 2.3.1
< 2.4.5
|
2.4.5
|
|
fast-uri
|
npm |
≥ 3.0.0
< 3.1.6
|
3.1.6
|
|
fast-uri
|
npm |
≥ 4.0.0
< 4.1.3
|
4.1.3
|
References
Frequently Asked Questions
What is CVE-2026-75975?
Which Fast uri versions are affected?
What version fixes CVE-2026-75975?
Is fast-uri affected?
What is the CVSS score of CVE-2026-75975?
What CWE is associated with CVE-2026-75975?
How can I check npm dependencies for CVE-2026-75975?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-f65p-4m7j-42xc",
"modified" : "2026-09-02T15:43:30Z",
"published" : "2026-09-02T15:43:30Z",
"aliases" : [ "CVE-2026-75975" ],
"summary" : "fast-uri vulnerable to server-side request forgery via malformed IPv6 normalization",
"details" : "### Impact\n\n`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. For example, `normalize('http://[::not-valid]/private')` returns `http://[::]/private`, and `[fc00::not-hex]` and `[fe80::not-hex]` collapse to `[fc00::]` and `[fe80::]`. An application that normalizes an untrusted URL before an outbound request, redirect, or host-policy check can be routed to a local or private address such as loopback (`::1`), unique-local, or link-local. Because `parse().error` is unset for these inputs, checking it does not protect the consumer.\n\n### Patches\n\nUpgrade to `fast-uri` 2.4.5, 3.1.6, or 4.1.3. Malformed IPv6 literals are now rejected with a host error instead of being normalized to a valid address.\n\n### Workarounds\n\nReject untrusted URLs whose host is a bracketed IPv6 literal before passing them to `fast-uri`, or route outbound requests against an explicit allowlist of addresses rather than trusting the normalized host.",
"severity" : [ {
"type" : "CVSS_V3",
"score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "npm",
"name" : "fast-uri"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "2.3.1"
}, {
"fixed" : "2.4.5"
} ]
} ]
}, {
"package" : {
"ecosystem" : "npm",
"name" : "fast-uri"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "3.0.0"
}, {
"fixed" : "3.1.6"
} ]
} ]
}, {
"package" : {
"ecosystem" : "npm",
"name" : "fast-uri"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "4.0.0"
}, {
"fixed" : "4.1.3"
} ]
} ]
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/fastify/fast-uri/security/advisories/GHSA-f65p-4m7j-42xc"
}, {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-75975"
}, {
"type" : "WEB",
"url" : "https://github.com/fastify/fast-uri/commit/3728465caacef4b16bc84b7d14760f1c8fe41595"
}, {
"type" : "WEB",
"url" : "https://github.com/fastify/fast-uri/commit/607bfbe953f28a14c2e06ae64aff38c81ca2937f"
}, {
"type" : "WEB",
"url" : "https://github.com/fastify/fast-uri/commit/9161eded1ff55fad9d9714c6ad6c0f0283547799"
}, {
"type" : "WEB",
"url" : "https://cna.openjsf.org/security-advisories.html"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/fastify/fast-uri"
}, {
"type" : "WEB",
"url" : "https://github.com/fastify/fast-uri/releases/tag/v2.4.5"
}, {
"type" : "WEB",
"url" : "https://github.com/fastify/fast-uri/releases/tag/v3.1.6"
}, {
"type" : "WEB",
"url" : "https://github.com/fastify/fast-uri/releases/tag/v4.1.3"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-20", "CWE-918" ],
"severity" : "HIGH",
"github_reviewed" : true,
"github_reviewed_at" : "2026-09-02T15:43:30Z",
"nvd_published_at" : "2026-08-24T10:16:40Z"
}
}