CVE-2026-75975
fast-uri is a URI parser for Node.js.
Published Aug 24, 2026 · updated Oct 15, 2026 · openjsf fast-uri
fast-uri is a URI parser for Node.js. Its custom parser for bracketed IPv6 literals does not validate the complete IPv6 grammar, so invalid trailing text in an authority can be silently discarded and a malformed attacker-controlled host is turned into a different valid IPv6 destination. For example, a bracketed literal with invalid trailing characters is normalized to the unspecified address, which a Node HTTP client then connects to a local service over loopback, and other malformed literals collapse to private-range addresses. No error is set on the parsed result, so an application checking the error field cannot detect the rewrite. An application that normalizes untrusted URLs before outbound requests, redirects, proxy routing, or address-policy enforcement can be redirected to a local or private IPv6 target, giving a server-side request forgery and address-policy bypass primitive. The affected versions are 2.3.1 up to but not including 2.4.5, 3.0.0 up to but not including 3.1.6, and 4.0.0 up to but not including 4.1.3. The issue is fixed in 2.4.5, 3.1.6, and 4.1.3, which validate bracketed IP literals against the full grammar and mark malformed literals as authority errors. Users should upgrade to a patched version.
Code
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Timeline
Detection, updates, and resolution for this record.
Aug 24, 2026 · NIST NVD
Detected
fast-uri is a URI parser for Node.js. Its custom parser for bracketed IPv6 literals does not validate the complete IPv6 grammar, so invalid trailing text in an authority can be silently discarded and a malformed attacker-controlled host is turned into a different valid IPv6 destination. For example, a bracketed literal with invalid trailing characters is normalized to the unspecified address, whic
Oct 14, 2026 · NIST NVD
Updated
fast-uri is a URI parser for Node.js. Its custom parser for bracketed IPv6 literals does not validate the complete IPv6 grammar, so invalid trailing text in an authority can be silently discarded and a malformed attacker-controlled host is turned into a different valid IPv6 destination. For example, a bracketed literal with invalid trailing characters is normalized to the unspecified address, whic
Oct 15, 2026 · OSV.dev
Fix available
node-ajv fixed in 8.20.0~ds+~cs7.1.4-1
Oct 15, 2026 · OSV.dev
Fix available
node-ajv fixed in 8.20.0~ds+~cs7.1.4-1
Oct 15, 2026 · OSV.dev
Updated
fast-uri is a URI parser for Node.js. Its custom parser for bracketed IPv6 literals does not validate the complete IPv6 grammar, so invalid trailing text in an authority can be silently discarded and a malformed attacker-controlled host is turned into a different valid IPv6 destination. For example, a bracketed literal with invalid trailing characters is normalized to the unspecified address, whic
Affected
- Debian:13 node-ajv8.12.0~ds+~2.1.1-5, 8.17.1~ds+~3.0.1+~3.1.0-1, 8.17.1~ds+~3.0.1+~3.1.0-2
- Debian:14 node-ajv0 → 8.20.0~ds+~cs7.1.4-1
- cpe openjsf/fast-uriversion unspecified
Sources
- CVE.orgVulnerability recordCVE-2026-75975
Official CVE identifier
cve.org - FIRST EPSSExploitation probabilityCVE-2026-75975
30-day exploitation probability 0.2%
first.org - NIST NVDVulnerability recordCVE-2026-75975
fast-uri is a URI parser for Node.js. Its custom parser for bracketed IPv6 literals does not validate the complete IPv6 grammar, so invalid trailing text in an authority can be silently discarded and a malformed attacker-controlled host is turned into a different valid IPv6 desti
nvd.nist.gov - OSV.devPackage advisoryDEBIAN-CVE-2026-75975osv.dev