CVE-2021-43519 and is rated Medium severity with a CVSS score of 5.5. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.
What to do next
Remediation and response
Microsoft Security Response Center guidance
Vendor revision: Aug 17, 2026
Vendor remediation details
CBL-Mariner Releases
Vendor-listed releases
5.4.4-1
1.6.27-2
5.2.1-5
18.2.2-3
CISA KEVNot listedBased on the latest collected catalog
EPSS1.2%Estimated 30-day exploitation probability
Ransomware useNot markedCISA KEV ransomware field
Threat actors0Source-linked actor relationships
Overview
What is CVE-2021-43519?
Stack overflow in lua_resume of ldo.c in Lua Interpreter 5.1.0~5.4.4 allows attackers to perform a Denial of Service via a crafted script file.