fast-uri <=3.1.2/4.0.0 Unicode IDN Canonicalization Bug
CVE-2026-13676 Published on June 29, 2026

fast-uri vulnerable to host confusion via failed IDN canonicalization
fast-uri versions 2.3.1 through 3.1.2 and 4.0.0 fail to canonicalize Unicode (IDN) hostnames for HTTP-family URLs. The IDN conversion path calls a helper that does not exist on the global URL constructor, silently leaving the host in its original Unicode form while normalize() and equal() still return values that differ from a WHATWG-compatible URL parser. Applications that use fast-uri to enforce host-based policy (denylists, loopback filtering, redirect validation, outbound proxy routing) before passing the same URL to Node's URL or fetch can be bypassed when the two implementations resolve the same input to different hosts. Patches: upgrade to fast-uri 3.1.3 for the 3.x line or 4.0.1 for the 4.x line. Workarounds: enforce host policy using the same URL parser used for the actual request, or reject non-ASCII hosts before policy checks.

NVD

Vulnerability Analysis

CVE-2026-13676 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality, a high impact on integrity, and no impact on availability.

Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
NONE
User Interaction:
NONE
Scope:
UNCHANGED
Confidentiality Impact:
NONE
Integrity Impact:
HIGH
Availability Impact:
NONE

Weakness Types

Interpretation Conflict

Product A handles inputs or steps differently than Product B, which causes A to perform incorrect actions based on its perception of B's state. This is generally found in proxies, firewalls, anti-virus software, and other intermediary devices that monitor, allow, deny, or modify traffic based on how the client or server is expected to behave.

Incorrect Behavior Order: Authorization Before Parsing and Canonicalization

If a web server does not fully parse requested URLs before it examines them for authorization, it may be possible for an attacker to bypass authorization protection. For instance, the character strings /./ and / both mean current directory. If /SomeDirectory is a protected directory and an attacker requests /./SomeDirectory, the attacker may be able to gain access to the resource if /./ is not converted to / before the authorization check is performed.


Products Associated with CVE-2026-13676

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Red Hat Confidential Compute Attestation
 
Red Hat Cryostat
 
Red Hat Migration Toolkit Applications
 
Red Hat Rhmt
 
Red Hat Multicluster Engine
 
Red Hat Network Observ Optr
 
Red Hat Openshift Lightspeed
 
Red Hat Openshift Pipelines
 
Red Hat Serverless
 
Red Hat Acm
 
Red Hat Amq Broker
 
Red Hat Ansible Automation Platform
 
Red Hat Apache Camel Hawtio
 
Red Hat Apicurio Registry
 
Red Hat Podman Desktop
 
Red Hat Connectivity Link
 
Red Hat Jboss Data Grid
 
Red Hat Rhdh
 
Red Hat Discovery
 
Red Hat Edge Manager
 
Red Hat Enterprise Linux (RHEL)
 
Red Hat Enterprise Linux Ai
 
Red Hat Openshift Ai
 
Red Hat Openshift
 
Red Hat Openshift Data Foundation
 
Red Hat Openshift Devspaces
 
Red Hat Container Native Virtualization
 
Red Hat Quay
 
Red Hat Satellite
 
Red Hat Ansible Portal
 

Affected Versions

fast-uri: Red Hat Edge Manager 1.1: Red Hat Edge Manager 1.1: Red Hat Edge Manager 1.1: Red Hat Edge Manager 1.1: Red Hat OpenShift Container Platform 4.20: Red Hat OpenShift Container Platform 4.21: Red Hat OpenShift Container Platform 4.22: Red Hat Quay 3.16: Red Hat Quay 3.9: Red Hat Confidential Compute Attestation: Red Hat Cryostat 4: Red Hat Cryostat 4: Red Hat Migration Toolkit for Applications 8: Red Hat Migration Toolkit for Containers: Red Hat Multicluster Engine for Kubernetes: Red Hat Network Observability Operator: Red Hat Network Observability Operator: Red Hat OpenShift Lightspeed: Red Hat OpenShift Lightspeed: Red Hat OpenShift Lightspeed: Red Hat OpenShift Lightspeed: Red Hat OpenShift Pipelines: Red Hat OpenShift Pipelines: Red Hat OpenShift Pipelines: Red Hat OpenShift Pipelines: Red Hat OpenShift Pipelines: Red Hat OpenShift Serverless: Red Hat OpenShift Serverless: Red Hat OpenShift Serverless: Red Hat OpenShift Serverless: Red Hat OpenShift Serverless: Red Hat OpenShift Serverless: Red Hat OpenShift Serverless: Red Hat OpenShift Serverless: Red Hat OpenShift Serverless: Red Hat Advanced Cluster Management for Kubernetes 2: Red Hat AMQ Broker 7: Red Hat Ansible Automation Platform 2: Red Hat Ansible Automation Platform 2: Red Hat Ansible Automation Platform 2: Red Hat Ansible Automation Platform 2: Red Hat Ansible Automation Platform 2: Red Hat Ansible Automation Platform 2: Red Hat Ansible Automation Platform 2: Red Hat Ansible Automation Platform 2: Red Hat Ansible Automation Platform 2: Red Hat Ansible Automation Platform 2: Red Hat build of Apache Camel - HawtIO 4: Red Hat build of Apicurio Registry 3: Red Hat build of Apicurio Registry 3: Red Hat Build of Podman Desktop: Red Hat Connectivity Link 1: Red Hat Data Grid 8: Red Hat Developer Hub: Red Hat Discovery 2: Red Hat Enterprise Linux 10: Red Hat Enterprise Linux 9: Red Hat Enterprise Linux AI (RHEL AI) 3: Red Hat Enterprise Linux AI (RHEL AI) 3: Red Hat Enterprise Linux AI (RHEL AI) 3: Red Hat Enterprise Linux AI (RHEL AI) 3: Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift Container Platform 4: Red Hat OpenShift Container Platform 4: Red Hat OpenShift Container Platform 4: Red Hat Openshift Data Foundation 4: Red Hat Openshift Data Foundation 4: Red Hat Openshift Data Foundation 4: Red Hat Openshift Data Foundation 4: Red Hat OpenShift Dev Spaces: Red Hat OpenShift Virtualization 4: Red Hat Satellite 6: Red Hat Satellite 6: Red Hat Satellite 6: Red Hat Satellite 6: Red Hat Satellite 6: Red Hat Satellite 6: Red Hat Satellite 6: Red Hat Self-service automation portal 2: Red Hat Self-service automation portal 2: