CVE-2026-16221

A flaw was found in fast-uri. This vulnerability arises because fast-uri does not correctly interpret backslash characters as authority delimiters in Uniform Resource Locators (URLs), unlike Node.js's native WHATWG URL parser. This discrepancy can cause applications that use fast-uri for security policy enforcement, such as allowlists or Server-Side Request Forgery (SSRF) filtering, to misidentify the intended host. Consequently, an attacker could bypass these security policies, potentially redirecting traffic to unintended internal or sensitive network destinations.

Important: This flaw in fast-uri allows for a security policy bypass due to inconsistent URL parsing between fast-uri and Node.js's native WHATWG URL parser. Applications within Red Hat Hardened Images that rely on fast-uri for host-based policy enforcement, such as allowlists or Server-Side Request Forgery (SSRF) filtering, can be misled by specially crafted URLs. This could enable an attacker to redirect traffic to unintended internal or sensitive network destinations.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.