In general, these flaws cannot be exploited through email in the Thunderbird product because scripting is disabled when reading mail, but are potentially risks in browser or browser-like contexts.
A use-after-free vulnerability in the Skia library can occur when creating a path, leading to a potentially exploitable crash.
An integer overflow vulnerability in the Skia library can occur after specific transform operations, leading to a potentially exploitable crash.
A buffer overflow vulnerability in the Skia library can occur with Canvas 2D acceleration on macOS. This issue was addressed by disabling Canvas 2D acceleration in Firefox ESR.
Note: this does not affect other versions and platforms where Canvas 2D acceleration is already disabled by default.
A flaw during verification of certain S/MIME signatures causes emails to be shown in Thunderbird as having a valid digital signature, even if the shown message contents aren't covered by the signature. The flaw allows an attacker to reuse a valid S/MIME signature to craft an email message with arbitrary content.