CVE-2026-16221
Description
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.
Statement
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.
Mitigation
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.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | High | N/A | High |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Understanding the Weakness (CWE)
Confidentiality,Access Control,Availability,Other
Technical Impact: Bypass Protection Mechanism; Gain Privileges or Assume Identity; Varies by Context
Attackers can bypass the security decision to access whatever is being protected. The consequences will depend on the associated functionality, but they can range from granting additional privileges to untrusted users to bypassing important security checks. Ultimately, this weakness may lead to exposure or modification of sensitive data, system crash, or execution of arbitrary code.
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