REDHAT-BUG-2509801: SSRF

Published Jul 31, 2026
·
Updated

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 Software

1 affected component
npm/fast-uri<4.1.2, <3.1.5, <2.4.4

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade fast-uri to a version that resolves this vulnerability.

    Fixed in 4.1.2
  2. Upgrade

    Upgrade fast-uri to a version that resolves this vulnerability.

    Fixed in 3.1.5
  3. Upgrade

    Upgrade fast-uri to a version that resolves this vulnerability.

    Fixed in 2.4.4

Event History

Jul 31, 2026
Data Sourced
via Red Hat·03:01 PM
DescriptionSeverityAffected Software

Contact

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