CVE-2026-13676

A flaw was found in fast-uri. This vulnerability occurs because fast-uri fails to properly convert Unicode (Internationalized Domain Name - IDN) hostnames for HTTP-family URLs. This can lead to a situation where security policies, such as denylists or redirect validations, are bypassed when applications use fast-uri to enforce these policies before passing the URL to another parser. A remote attacker could exploit this to circumvent security controls and potentially access unauthorized resources or perform malicious redirects.

This Important flaw in fast-uri allows a remote attacker to bypass host-based security policies. Applications that rely on fast-uri for URL parsing and policy enforcement, such as denylists or redirect validations, can be circumvented due to inconsistent handling of Unicode hostnames. This discrepancy between fast-uri and other URL parsers could lead to unauthorized resource access or malicious redirects in affected Red Hat products.

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.