CVE-2025-66412

A Stored Cross-Site Scripting (XSS) vulnerability has been identified in the Angular Template Compiler. It occurs because the compiler's internal security schema is incomplete, allowing attackers to bypass Angular's built-in security sanitization. Specifically, the schema fails to classify certain URL-holding attributes (e.g., those that could contain javascript: URLs) as requiring strict URL security, enabling the injection of malicious scripts.

Additionally, a related vulnerability exists involving SVG animation elements (<animate>, <set>, <animateMotion>, <animateTransform>). The attributeName attribute on these elements was not properly validated, allowing attackers to dynamically target security-sensitive attributes like href or xlink:href on other elements. By binding attributeName to "href" and providing a javascript: URL in the values or to attribute, an attacker could bypass sanitization and execute arbitrary code.

Attributes confirmed to be vulnerable include:

• SVG-related attributes: (e.g., xlink:href), and various MathML attributes (e.g., math|href, annotation|href).
• SVG animation attributeName attribute when bound to "href" or "xlink:href".

When template binding is used to assign untrusted, user-controlled data to these attributes (e.g., [attr.xlink:href]="maliciousURL" or <animate [attributeName]="'href'" [values]="maliciousURL">), the compiler incorrectly falls back to a non-sanitizing context or fails to block the dangerous attribute assignment. This allows an attacker to inject a javascript:URL payload. Upon user interaction (like a click) on the element, or automatically in the case of animations, the malicious JavaScript executes in the context of the application's origin.

Attack Preconditions

• The victim's Angular application must render data derived from untrusted input (e.g., from a database or API) and bind it to one of the unsanitized URL attributes or the attributeName of an SVG animation element.
• The victim must perform a user interaction (e.g., clicking) on the compromised element for the stored script to execute, or the animation must trigger the execution.

Workarounds

If you cannot upgrade, you can workaround the issue by ensuring that any data bound to the vulnerable attributes is never sourced from untrusted user input (e.g., database, API response, URL parameters).

• Avoid Affected Template Bindings: Specifically avoid using template bindings (e.g., [attr.xlink:href]="maliciousURL") to assign untrusted data to the vulnerable SVG/MathML attributes.
• Avoid Dynamic attributeName on SVG Animations: Do not bind untrusted data to the attributeName attribute of SVG animation elements (<animate>, <set>, etc.).
• Enable Content Security Policy (CSP): Configure a robust CSP header that disallows javascript: URLs.

When exploited, this vulnerability allows an attacker to execute arbitrary code within the context of the vulnerable application's domain. This enables:

• Session Hijacking: Stealing session cookies and authentication tokens.
• Data Exfiltration: Capturing and transmitting sensitive user data.
• Unauthorized Actions: Performing actions on behalf of the user.

Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.

Kodem intelligence

• 19.2.17
• 20.3.15
• 21.0.2

1. What is CVE-2025-66412? CVE-2025-66412 is a high-severity cross-site scripting (XSS) vulnerability in @angular/compiler (npm), affecting versions >= 21.0.0-next.0, < 21.0.2. It is fixed in 21.0.2, 20.3.15, 19.2.17. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. Which versions of @angular/compiler are affected by CVE-2025-66412? @angular/compiler (npm) versions >= 21.0.0-next.0, < 21.0.2 is affected.
3. Is there a fix for CVE-2025-66412? Yes. CVE-2025-66412 is fixed in 21.0.2, 20.3.15, 19.2.17. Upgrade to this version or later.
4. Is CVE-2025-66412 exploitable, and should I be worried? Whether CVE-2025-66412 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
5. What actually determines whether CVE-2025-66412 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
6. How do I fix CVE-2025-66412?
   • Upgrade @angular/compiler to 21.0.2 or later
   • Upgrade @angular/compiler to 20.3.15 or later
   • Upgrade @angular/compiler to 19.2.17 or later