CVE-2026-43915
Description
A flaw was found in Coturn. A remote attacker can exploit a stored Cross-Site Scripting (XSS) vulnerability in the web-admin HTTPS interface by creating a TURN allocation with a crafted username. This allows the attacker to inject malicious HTML or JavaScript code. When an authenticated web-admin user views the TURN session list, the injected code executes, potentially leading to information disclosure or unauthorized actions within the web-admin interface.
Statement
This Moderate flaw in Coturn's web-admin HTTPS interface allows a remote attacker to perform stored Cross-Site Scripting. Exploitation requires an attacker to create a TURN allocation with a specially crafted username, which then executes when an authenticated administrator views the TURN session list. While requiring administrator interaction, configurations with anonymous TURN access could broaden the attack surface by not requiring TURN credentials.
Mitigation
Restrict network access to the Coturn web-admin HTTPS interface to trusted administrative networks. Additionally, ensure that Coturn is configured to require authentication for all TURN allocations, preventing unauthenticated users from creating allocations with crafted usernames. This typically involves removing or avoiding the --no-auth option in the Coturn configuration. A restart of the Coturn service is necessary for these configuration changes to take effect.
Understanding the Weakness (CWE)
Access Control,Confidentiality
Technical Impact: Bypass Protection Mechanism; Read Application Data
The most common attack performed with cross-site scripting involves the disclosure of private information stored in user cookies, such as session information. Typically, a malicious user will craft a client-side script, which -- when parsed by a web browser -- performs some activity on behalf of the victim to an attacker-controlled system (such as sending all site cookies to a given E-mail address). This could be especially dangerous to the site if the victim has administrator privileges to manage that site. This script will be loaded and run by each user visiting the web site. Since the site requesting to run the script has access to the cookies in question, the malicious script does also.
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
In some circumstances it may be possible to run arbitrary code on a victim's computer when cross-site scripting is combined with other flaws, for example, "drive-by hacking."
Confidentiality,Integrity,Availability,Access Control
Technical Impact: Execute Unauthorized Code or Commands; Bypass Protection Mechanism; Read Application Data
The consequence of an XSS attack is the same regardless of whether it is stored or reflected. The difference is in how the payload arrives at the server. XSS can cause a variety of problems for the end user that range in severity from an annoyance to complete account compromise. Some cross-site scripting vulnerabilities can be exploited to manipulate or steal cookies, create requests that can be mistaken for those of a valid user, compromise confidential information, or execute malicious code on the end user systems for a variety of nefarious purposes. Other damaging attacks include the disclosure of end user files, installation of Trojan horse programs, redirecting the user to some other page or site, running "Active X" controls (under Microsoft Internet Explorer) from sites that a user perceives as trustworthy, and modifying presentation of content.
Frequently Asked Questions
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