CVE-2026-18446: fast-uri vulnerable to host confusion via backslash authority introducer
Fixed in 4.1.2 · Affected: fast-uri before 4.1.2 · Exploitation: unlikely (under 1%)
Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.
Higher than 32% of scored CVEs
DescriptionCVE.org
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.
Affected products1
From the CVE record. A product or version that is not listed is unknown, not unaffected.
- fast-uri · fast-urifrom 4.0.0 before 4.1.2; from 3.0.0 before 3.1.5; before 2.4.4
On the Atlas
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CoverageNo articles yet
No CyberSIXT article names CVE-2026-18446 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.