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High severity7.5NVD Advisory· Published Jul 31, 2026· Updated Sep 2, 2026

CVE-2026-18446

CVE-2026-18446

Description

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.

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Affected packages

Versions sourced from the GitHub Security Advisory.

PackageAffected versionsPatched versions
fast-urinpm
< 2.4.42.4.4
fast-urinpm
>= 3.0.0, < 3.1.53.1.5
fast-urinpm
>= 4.0.0, < 4.1.24.1.2

Affected products

43

Patches

Vulnerability mechanics

References

6

News mentions

0

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