CVE-2024-8373: AngularJS srcset XSS Vulnerability

CVE-2024-8373 Overview

CVE-2024-8373 is a Missing Input Sanitization vulnerability affecting AngularJS, where improper sanitization of the [srcset] attribute in <source> HTML elements allows attackers to bypass common image source restrictions. This security flaw can lead to Content Spoofing attacks, potentially enabling malicious actors to inject unauthorized content into web applications built with AngularJS.

Critical Impact

This vulnerability affects all versions of AngularJS. Importantly, the AngularJS project has reached End-of-Life status and will not receive any updates to address this issue, leaving applications permanently vulnerable unless they migrate to a supported framework.

Affected Products

• AngularJS (all versions)
• NetApp Active IQ Unified Manager for Linux
• NetApp Active IQ Unified Manager for vSphere
• NetApp Active IQ Unified Manager for Windows

Discovery Timeline

• 2024-09-09 - CVE-2024-8373 published to NVD
• 2025-11-20 - Last updated in NVD database

Technical Details for CVE-2024-8373

Vulnerability Analysis

This vulnerability stems from insufficient sanitization of the srcset attribute within <source> HTML elements when processed by AngularJS. The srcset attribute is used in responsive web design to specify different image sources for various display conditions. AngularJS's sanitization routines fail to properly validate and sanitize values assigned to this attribute, creating an avenue for attackers to bypass the framework's built-in security controls.

The attack can be executed remotely over a network and requires user interaction to be successful. When exploited, this vulnerability compromises the integrity of the affected application by allowing unauthorized content to be displayed to users, though it does not directly impact confidentiality or availability.

Root Cause

The root cause of CVE-2024-8373 lies in AngularJS's HTML sanitization logic, which does not adequately handle the srcset attribute of <source> elements. While AngularJS implements sanitization for common attributes like src and href, the srcset attribute was not given the same level of scrutiny. This oversight allows specially crafted values to pass through sanitization checks, enabling attackers to inject arbitrary image sources or content that would otherwise be blocked by the framework's security policies.

This vulnerability is classified under CWE-791 (Incomplete Filtering of Special Elements), indicating that the sanitization routine fails to filter all potentially dangerous input patterns.

Attack Vector

The attack leverages the network-accessible nature of web applications built with AngularJS. An attacker can craft malicious input containing specially formatted srcset attribute values that bypass AngularJS's sanitization filters. When a user interacts with the application and renders content containing the malicious payload, the unauthorized content is displayed.

The attack scenario involves injecting content through user-controllable input fields that are eventually rendered in <source> elements with srcset attributes. By exploiting the sanitization bypass, attackers can point the srcset to arbitrary external resources, effectively spoofing legitimate content with attacker-controlled material.

For technical demonstration of this vulnerability, a proof-of-concept is available at the CodePen Demo Repository. Additional technical details can be found in the HeroDevs Vulnerability Directory.

Detection Methods for CVE-2024-8373

Indicators of Compromise

• Unusual or unexpected srcset attribute values in <source> elements pointing to external or untrusted domains
• User reports of content appearing different than expected or displaying unauthorized images
• Web application logs showing injection attempts containing srcset attribute manipulation patterns

Detection Strategies

• Implement Content Security Policy (CSP) headers with strict img-src directives to detect and block unauthorized image sources
• Deploy web application firewalls (WAF) with rules to detect srcset attribute manipulation attempts
• Conduct regular code reviews and security audits focusing on user input handling in AngularJS templates

Monitoring Recommendations

• Monitor web server logs for requests containing unusual srcset patterns or attempts to load images from untrusted sources
• Set up alerting for CSP violation reports that may indicate exploitation attempts
• Track dependency usage to identify applications still running vulnerable AngularJS versions

How to Mitigate CVE-2024-8373

Immediate Actions Required

• Inventory all applications using AngularJS and prioritize migration to Angular (2+) or other actively maintained frameworks
• Implement Content Security Policy headers with restrictive img-src directives to limit image sources to trusted domains
• Apply additional server-side input validation and sanitization for any user-controlled content that may be rendered in HTML
• Review and audit all usage of <source> elements with dynamic srcset attributes in AngularJS applications

Patch Information

No official patch is available for this vulnerability. AngularJS has reached End-of-Life status and will not receive security updates. Organizations must migrate to supported frameworks such as Angular (version 2 and above) to address this vulnerability permanently.

For NetApp Active IQ Unified Manager users, refer to the NetApp Security Advisory NTAP-20241122-0003 for vendor-specific guidance. Debian users should consult the Debian LTS Announcement for distribution-specific information.

Workarounds

• Implement strict Content Security Policy headers to restrict image sources to known trusted domains
• Add server-side validation to reject or sanitize any user input containing srcset attribute values before rendering
• Consider using a custom AngularJS directive that enforces additional sanitization for srcset attributes
• Deploy a web application firewall with custom rules to filter malicious srcset payloads

# Example Content Security Policy header configuration
# Add to web server configuration (Apache/Nginx)
# This restricts image sources to your domain only

# Apache (.htaccess or httpd.conf)
Header set Content-Security-Policy "img-src 'self' https://trusted-cdn.example.com;"

# Nginx (nginx.conf)
add_header Content-Security-Policy "img-src 'self' https://trusted-cdn.example.com;";