The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has recently added a medium-severity cross-site scripting (XSS) vulnerability, CVE-2020-11023, to its Known Exploited Vulnerabilities (KEV) catalog. This five-year-old flaw, found in the widely-used jQuery JavaScript library, has been flagged due to active exploitation, posing significant risks to systems still using outdated versions of the library.
CVE-2020-11023
CVE-2020-11023 is a vulnerability with a CVSS score ranging between 6.1 and 6.9, indicating medium severity. It enables attackers to execute arbitrary code by exploiting jQuery’s DOM manipulation methods such as .html(), .append(), and others. Specifically, the flaw arises when HTML containing <option> elements from untrusted sources is passed to these methods, even if sanitized. This creates opportunities for malicious code execution, which can compromise the integrity of web applications.
The vulnerability was initially addressed in April 2020 with the release of jQuery version 3.5.0. Developers are advised to upgrade to this or later versions to mitigate the risk. For environments where upgrading is not immediately feasible, a workaround involves using the DOMPurify library with the SAFE_FOR_JQUERY flag enabled. This ensures proper sanitization of HTML strings before they interact with jQuery methods.
Evidence of Active Exploitation
While CISA’s advisory does not provide in-depth details about the specific nature of exploitation or identify the threat actors leveraging this flaw, it aligns with prior warnings about its potential misuse. Notably, Dutch cybersecurity firm EclecticIQ reported in February 2024 that a malicious campaign exploiting vulnerabilities in Ivanti appliances utilized an outdated jQuery version vulnerable to CVE-2020-11023, along with two other flaws, CVE-2020-11022 and CVE-2019-11358.
These findings underscore the importance of maintaining updated libraries and applying security patches promptly to minimize exposure to such threats. The inclusion of this vulnerability in the KEV catalog highlights its relevance and the necessity for organizations to address it without delay.
CISA’s Directive for Federal Agencies
In accordance with Binding Operational Directive (BOD) 22-01, Federal Civilian Executive Branch (FCEB) agencies are required to remediate CVE-2020-11023 by February 13, 2025. This directive ensures that federal systems are safeguarded against known and actively exploited vulnerabilities, reinforcing the resilience of critical infrastructure and public sector networks.
Mitigation
Organizations leveraging jQuery in their web applications should take immediate steps to address this vulnerability. Below are actionable recommendations to enhance security and reduce the risk of exploitation:
Update jQuery to the Latest Version: Ensure that your web applications are running jQuery version 3.5.0 or newer. This update addresses CVE-2020-11023 and other vulnerabilities.
Implement DOMPurify for Input Sanitization: For scenarios where upgrading jQuery is not feasible, use the DOMPurify library with the
SAFE_FOR_JQUERYflag enabled. This helps sanitize untrusted HTML strings before they are processed by jQuery methods.Conduct Regular Security Audits: Periodically review your application dependencies and identify outdated or vulnerable libraries. Use tools like npm audit or Snyk to automate this process.
Monitor Threat Intelligence Feeds: Stay informed about emerging threats and vulnerabilities by subscribing to advisories from CISA, security vendors, and other trusted sources. This ensures timely awareness and proactive mitigation.
Educate Development Teams: Provide training to developers on secure coding practices, including the risks associated with third-party libraries. Encourage adherence to secure development lifecycle (SDLC) principles.
Implications and Lessons Learned
The exploitation of CVE-2020-11023 underscores a persistent challenge in cybersecurity: the reliance on outdated software components. jQuery, a ubiquitous library in web development, exemplifies how legacy vulnerabilities can remain exploitable years after patches are released. Organizations must prioritize regular updates and adopt robust vulnerability management practices to reduce their attack surface.
Additionally, the advisory serves as a reminder that no application component—however widely used or trusted—is immune to exploitation. As cyberattacks grow increasingly sophisticated, it’s imperative to adopt a multi-layered security approach, including:
Zero Trust Architecture: Limit access privileges and continuously verify the identity of users and devices.
Runtime Application Self-Protection (RASP): Incorporate tools that detect and mitigate threats during runtime.
Proactive Patch Management: Establish processes for promptly applying security updates across all systems.
Conclusion
CISA’s addition of CVE-2020-11023 to the KEV catalog serves as a critical wake-up call for organizations using outdated versions of jQuery. The potential for arbitrary code execution through this vulnerability highlights the risks associated with unpatched software. By updating to the latest jQuery version, implementing robust sanitization measures, and adhering to best practices in security, organizations can safeguard their web applications against this and similar threats.
With the February 2025 remediation deadline looming for federal agencies, the message is clear: proactive measures today can prevent significant security breaches tomorrow.
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