CVE-2025-2336: AngularJS ngSanitize XSS Vulnerability

CVE-2025-2336 Overview

CVE-2025-2336 is an input validation vulnerability in AngularJS's ngSanitize module that allows attackers to bypass common image source restrictions through improper sanitization of href and xlink:href attributes in <image> SVG elements. This vulnerability enables content spoofing attacks and can negatively impact application performance by allowing the injection of oversized or slow-loading images.

The AngularJS project has reached End-of-Life status and will not receive any updates to address this security issue. Organizations still using AngularJS should evaluate migration strategies or consider commercial support options for continued security updates.

Critical Impact

Attackers can bypass image source restrictions to perform content spoofing attacks and potentially cause denial of service through resource-intensive image loading in applications using AngularJS ngSanitize module.

Affected Products

• AngularJS versions >= 1.3.1
• Applications using the ngSanitize module for SVG content processing
• Web applications with user-controlled SVG content rendering

Discovery Timeline

• 2025-06-04 - CVE-2025-2336 published to NVD
• 2025-11-03 - Last updated in NVD database

Technical Details for CVE-2025-2336

Vulnerability Analysis

This vulnerability stems from incomplete sanitization logic within the ngSanitize module when processing SVG <image> elements. The sanitization routines fail to properly validate and restrict the values assigned to href and xlink:href attributes, which are used to specify external image sources in SVG content.

When user-controlled SVG content is processed through ngSanitize, an attacker can craft malicious SVG payloads that include <image> elements with arbitrary URLs in these attributes. The sanitizer's allowlist-based approach does not adequately cover these specific attribute combinations within the SVG namespace.

The vulnerability is classified under CWE-791 (Incomplete Filtering of Special Elements), indicating that the sanitization logic fails to account for all potentially dangerous element and attribute combinations that could be leveraged for attack purposes.

Root Cause

The root cause lies in the incomplete implementation of SVG attribute sanitization within the ngSanitize module. While the module implements filtering for many dangerous elements and attributes, it does not properly handle the href and xlink:href attributes specifically within <image> SVG elements.

The xlink:href attribute uses XML namespacing, which may have been overlooked during the original sanitization implementation. Additionally, the dual nature of image source specification in SVG (both href and xlink:href can be used) creates multiple attack surfaces that must be defended simultaneously.

Attack Vector

The attack vector is network-based, requiring no authentication or user interaction. An attacker can exploit this vulnerability in scenarios where:

1. The application accepts user-supplied SVG content
2. The content is processed through the ngSanitize module
3. The sanitized output is rendered in the browser

By embedding malicious <image> elements with crafted href or xlink:href values, attackers can:

• Content Spoofing: Display arbitrary external images within the trusted application context, potentially misleading users
• Resource Exhaustion: Reference extremely large images or slow endpoints to degrade application performance
• Information Gathering: Reference attacker-controlled URLs to track when and where the malicious content is rendered

The vulnerability mechanism involves crafting SVG content with <image> elements containing arbitrary URLs. When this content passes through ngSanitize, the malicious attributes are not properly stripped or validated. A demonstration of this behavior is available through the CodePen Demo Project provided by the security researchers.

Detection Methods for CVE-2025-2336

Indicators of Compromise

• Presence of unexpected <image> elements within rendered SVG content
• SVG content containing href or xlink:href attributes pointing to external domains
• Unusual network requests to external image resources originating from SVG rendering
• User reports of unexpected or suspicious images appearing in the application

Detection Strategies

• Implement Content Security Policy (CSP) monitoring to detect unauthorized image sources
• Deploy web application firewall rules to inspect incoming SVG content for suspicious <image> elements
• Monitor application logs for rendering errors or unusual image loading patterns
• Conduct regular code audits to identify usage of vulnerable AngularJS versions and ngSanitize module

Monitoring Recommendations

• Enable CSP violation reporting to capture attempts to load images from unauthorized sources
• Monitor network traffic for unexpected outbound requests during SVG content rendering
• Implement client-side error tracking to identify performance degradation from malicious image loading
• Track AngularJS version usage across all applications to maintain visibility of vulnerable deployments

How to Mitigate CVE-2025-2336

Immediate Actions Required

• Inventory all applications using AngularJS ngSanitize module
• Implement additional server-side SVG sanitization before content reaches the AngularJS layer
• Deploy Content Security Policy headers with strict img-src directives
• Consider migrating to a modern, actively maintained framework such as Angular (v2+)

Patch Information

AngularJS has reached End-of-Life and will not receive official patches for this vulnerability. Organizations should consider the following alternatives:

• Migration: Transition to Angular (v2+) or another actively maintained framework
• Commercial Support: HeroDevs offers Never-Ending Support (NES) for AngularJS, which includes security patches for EOL software
• Defense in Depth: Implement compensating controls at other layers of the application stack

A security update is available for Debian LTS users as announced in the Debian LTS Announcement.

Workarounds

• Implement server-side SVG sanitization using libraries that explicitly handle <image> element attributes
• Configure Content Security Policy with restrictive img-src directives to limit allowed image sources
• Strip or reject SVG content containing <image> elements if not required for application functionality
• Consider disabling SVG rendering entirely for user-supplied content where feasible

# Example CSP header configuration to restrict image sources
# Add to web server configuration (Apache/Nginx) or application headers

# Apache configuration
Header set Content-Security-Policy "default-src 'self'; img-src 'self' https://trusted-cdn.example.com; script-src 'self'"

# Nginx configuration
add_header Content-Security-Policy "default-src 'self'; img-src 'self' https://trusted-cdn.example.com; script-src 'self'";