CVE-2026-18446

fast-uri before 4.1.2, 3.1.5, and 2.4.4 requires a literal double forward slash to recognize a URI authority, so a reference that uses a backslash based introducer in place of it (backslash backslash, forward slash backslash, or backslash forward slash) is parsed with no authority and folds into the path. Node's native WHATWG URL parser instead treats a backslash as interchangeable with a forward slash for special schemes, so the two parsers extract different hosts from the same input. Applications that use fast-uri to enforce host based policy such as allowlists, SSRF filtering, or redirect validation before passing the same URL into Node's URL or fetch consumers can be steered to an unintended host. Upgrade to fast-uri 4.1.2, 3.1.5, or 2.4.4.

CVSS v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact HIGH

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://cna.openjsf.org/security-advisories.html	Vendor Advisory
https://github.com/fastify/fast-uri/security/advisories/GHSA-7p8r-x3mc-p8w7	Vendor Advisory

Configurations

Configuration 1 (hide)

OR	cpe:2.3:a:openjsf:fast-uri::::::node.js::*
	cpe:2.3:a:openjsf:fast-uri::::::node.js::*
	cpe:2.3:a:openjsf:fast-uri::::::node.js::*

History

No history.

Information

Published : 2026-07-31 15:16

Updated : 2026-09-02 14:42

NVD link : CVE-2026-18446

Mitre link : CVE-2026-18446

CVE.ORG link : CVE-2026-18446

JSON object : View

Products Affected

openjsf

fast-uri

CWE

CWE-436

Interpretation Conflict

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