In ytnef 1.9.3, the TNEFSubjectHandler function in lib/ytnef.c allows remote attackers to cause a denial-of-service (and potentially code execution) due to a double free which can be triggered via a crafted file.
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2021-3403.json"