CISA Adds Five-Year-Old jQuery XSS Flaw to Exploited Vulnerabilities List

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) on Thursday placed a now-patched security flaw impacting the popular jQuery JavaScript library to its Known Exploited Vulnerabilities (KEV) catalog, based on evidence of active exploitation.

The medium-severity vulnerability is CVE-2020-11023 (CVSS score: 6.1/6.9), a nearly five-year-old cross-site scripting (XSS) bug that could be exploited to achieve arbitrary code execution.

“Passing HTML containing elements from untrusted sources – even after sanitizing them – to one of jQuery’s DOM manipulation methods (i.e. .html(), .append(), and others) may execute untrusted code,” according to a GitHub advisory released for the flaw.

The problem was addressed in jQuery version 3.5.0 released in April 2020. A workaround for CVE-2020-11023 involves using DOMPurify with the SAFE_FOR_JQUERY flag set to sanitize the HTML string before passing it to a jQuery method.

As is typically the case, the advisory from CISA is lean on details about the specific nature of exploitation and the identity of threat actors weaponizing the shortcoming. Nor are there any recent public reports related to attacks that leverage the flaw in question.

That said, there are reports that vulnerability has been exploited by threat actors like APT1 (aka Brown Fox and Comment Panda) and APT27 (aka Brown Worm and Emissary Panda), per reports from Health-ISAC and Tenable.

Dutch security firm EclecticIQ also revealed in February 2024 that the command-and-control (C2) addresses associated with a malicious campaign exploiting security flaws in Ivanti appliances ran a version of JQuery that was susceptible to at least one of the three flaws, CVE-2020-11023, CVE-2020-11022, and CVE-2019-11358.

Pursuant to Binding Operational Directive (BOD) 22-01, Federal Civilian Executive Branch (FCEB) agencies are recommended to remediate the identified flaw by February 13, 2025, to secure their networks against active threats.

(The story was updated after publication to include references to reports highlighting exploitation of CVE-2020-11023.)