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.
Metrics
Affected Vendors & Products
References
History
Fri, 31 Jul 2026 19:30:00 +0000
| Type | Values Removed | Values Added |
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| Metrics |
ssvc
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Fri, 31 Jul 2026 15:45:00 +0000
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| First Time appeared |
Fast-uri
Fast-uri fast-uri |
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| Vendors & Products |
Fast-uri
Fast-uri fast-uri |
Fri, 31 Jul 2026 14:45:00 +0000
| Type | Values Removed | Values Added |
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| 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. | |
| Title | fast-uri vulnerable to host confusion via backslash authority introducer | |
| Weaknesses | CWE-436 | |
| References |
| |
| Metrics |
cvssV3_1
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Status: PUBLISHED
Assigner: openjs
Published:
Updated: 2026-07-31T17:47:35.325Z
Reserved: 2026-07-30T22:28:08.097Z
Link: CVE-2026-18446
Updated: 2026-07-31T17:47:30.658Z
No data.
No data.
OpenCVE Enrichment
Updated: 2026-07-31T15:30:03Z