The US cybersecurity agency CISA on Thursday added an old jQuery flaw tracked as CVE-2020-11023 to its Known Exploited Vulnerabilities (KEV) catalog. 

CVE-2020-11023 was disclosed in April 2020. The vulnerability has been described as a medium-severity XSS issue that can be exploited for arbitrary code execution. 

jQuery, a library designed to make it easier to use JavaScript, is widely used. After the vulnerability was disclosed, several major organizations published advisories to inform customers about its impact on their products, including Linux distributions, F5, IBM, and Atlassian.

It’s unclear why CISA has added CVE-2020-11023 to its KEV catalog now. There do not appear to be any recent reports describing exploitation of the vulnerability, and the agency typically does not share information on the attacks involving exploitation of flaws added to the KEV catalog.

However, SecurityWeek has found several older reports indicating that the vulnerability had been exploited by the Chinese state-sponsored threat actor tracked as APT1, whose existence came to light more than a decade ago. 

Tenable reported in 2021 that CVE-2020-11023 was one of the several vulnerabilities chained by APT1 to fully compromise targeted systems.

It’s unclear if CISA has evidence of more recent attacks or if it has added CVE-2020-11023 to its list based on these older reports. 

The agency has instructed federal agencies to check whether they are impacted by the jQuery vulnerability and take action by February 13. 

Related: CISA Warns of Second BeyondTrust Vulnerability Exploited in Attacks

Related: CISA Warns of Mitel MiCollab Vulnerabilities Exploited in Attacks

Related: CISA Warns of Exploited Adobe ColdFusion, Windows Vulnerabilities