USN-4936-1: Thunderbird vulnerabilities

Multiple security issues were discovered in Thunderbird. If a user were tricked into opening a specially crafted website in a browsing context, an attacker could potentially exploit these to cause a denial of service, obtain sensitive information, or execute arbitrary code. (CVE-2021-23968, CVE-2021-23969, CVE-2021-23973, CVE-2021-23978) It was discovered that Thunderbird may keep key material in memory in some circumstances. A local attacker could potentially exploit this to obtain private keys. (CVE-2021-29950)