CVE-2023-31973 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: Sep 27, 2026
Release Notes
CISA KEVNot listedBased on the latest collected catalog
EPSS0.3%Estimated 30-day exploitation probability
Ransomware useNot markedCISA KEV ransomware field
Threat actors0Source-linked actor relationships
Overview
What is CVE-2023-31973?
yasm v1.3.0 was discovered to contain a use after free via the function expand_mmac_params at /nasm/nasm-pp.c. Note: Multiple third parties dispute this as a bug and not a vulnerability according to the YASM security policy.