CVE-2020-7656 Overview
CVE-2020-7656 is a Cross-Site Scripting (XSS) vulnerability affecting jQuery versions prior to 1.9.0. The vulnerability exists in the load method, which fails to properly recognize and sanitize <script> HTML tags that contain a whitespace character before the closing bracket (e.g., </script >). This parsing flaw allows attackers to inject and execute malicious JavaScript code in the context of a victim's browser session.
Critical Impact
Applications using vulnerable jQuery versions are susceptible to XSS attacks that can lead to session hijacking, credential theft, defacement, and malware distribution through the improper handling of script tags in the load method.
Affected Products
- jQuery versions prior to 1.9.0
- Oracle PeopleSoft Enterprise PeopleTools 8.58
- NetApp Active IQ Unified Manager (Linux, VMware vSphere, Windows)
- NetApp Cloud Backup
- NetApp OnCommand System Manager
- NetApp Snap Creator Framework
- Juniper Junos 21.2
Discovery Timeline
- 2020-05-19 - CVE-2020-7656 published to NVD
- 2024-11-21 - Last updated in NVD database
Technical Details for CVE-2020-7656
Vulnerability Analysis
This Cross-Site Scripting vulnerability stems from insufficient input sanitization within jQuery's load method. The load method is commonly used to fetch HTML content from a server and insert it into the DOM. When processing the returned content, the method attempts to identify and remove potentially dangerous <script> tags to prevent script execution.
However, the sanitization logic uses a regex pattern that fails to account for whitespace characters within the closing script tag. When an attacker includes a space before the closing bracket (</script >), the tag evades detection and the enclosed JavaScript code is executed in the victim's browser context.
The vulnerability requires user interaction, as the victim must visit a page that loads attacker-controlled content. Once triggered, the attacker can execute arbitrary JavaScript, potentially stealing session cookies, performing actions on behalf of the user, or redirecting them to malicious sites.
Root Cause
The root cause is inadequate input validation in the load method's HTML parsing logic. The regex pattern used to identify and strip script tags does not account for variations in HTML tag formatting, specifically whitespace before the closing bracket. HTML parsers are generally permissive and accept </script > as a valid closing tag, but jQuery's sanitization routine does not follow the same permissive parsing, creating a security gap that attackers can exploit.
Attack Vector
The attack is network-based and requires an attacker to control or inject content that will be processed by the vulnerable load method. Attack scenarios include:
- Reflected XSS: An attacker crafts a malicious URL containing the XSS payload that, when clicked by a victim, loads content with the obfuscated script tag
- Stored XSS: An attacker stores malicious content containing </script > tags in a database, which is later retrieved and rendered by the load method
- Man-in-the-Middle: An attacker intercepts network traffic and injects the malicious script tag into responses that will be processed by the vulnerable method
The payload format uses the whitespace-obfuscated script tag:
<script >alert('XSS')</script >
The space before the closing bracket bypasses jQuery's sanitization, allowing the script to execute.
Detection Methods for CVE-2020-7656
Indicators of Compromise
- Presence of script tags with whitespace variations (</script >) in application logs or HTTP traffic
- Unexpected JavaScript execution or DOM manipulation on pages using jQuery's load method
- Anomalous outbound requests from client browsers to unknown domains
- User reports of unexpected behavior such as pop-ups, redirects, or session termination
Detection Strategies
- Implement Content Security Policy (CSP) headers with strict script-src directives to detect and block inline script execution attempts
- Deploy Web Application Firewalls (WAF) with rules to detect script tag variations including whitespace obfuscation
- Monitor JavaScript error logs for unexpected script execution patterns
- Use Software Composition Analysis (SCA) tools to identify applications using jQuery versions prior to 1.9.0
Monitoring Recommendations
- Enable detailed logging for all requests processed by jQuery's load method
- Set up alerts for HTML responses containing suspicious script tag patterns
- Implement client-side security monitoring to detect unexpected script execution
- Regularly scan application dependencies to identify vulnerable jQuery versions
How to Mitigate CVE-2020-7656
Immediate Actions Required
- Upgrade jQuery to version 1.9.0 or later across all affected applications
- Audit all usage of the load method to identify potentially vulnerable code paths
- Implement server-side input validation to sanitize HTML content before it reaches the client
- Deploy Content Security Policy headers to provide defense-in-depth against XSS attacks
Patch Information
The vulnerability was addressed in jQuery version 1.9.0 by improving the script tag sanitization logic in the load method. Organizations should upgrade to jQuery 1.9.0 or later, though the latest stable version is strongly recommended for comprehensive security coverage.
For vendor-specific patches, consult the following resources:
Workarounds
- Avoid using jQuery's load method for untrusted content until patching is complete
- Implement server-side sanitization that normalizes and strips all script tags regardless of whitespace variations
- Use Content Security Policy with strict script-src directives to prevent inline script execution
- Consider replacing the load method with safer alternatives that do not execute scripts from loaded content
# Check jQuery version in your project
grep -r "jquery" package.json bower.json
npm list jquery
# Update jQuery to latest version
npm update jquery
# Or specify minimum safe version
npm install jquery@">=1.9.0"
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
