Content Security Policy (CSP) is not applied correctly to all parts of multipart content sent with the “multipart/x-mixed-replace” MIME type. This could allow for script to run where CSP should block it, allowing for cross-site scripting (XSS) and other attacks. This vulnerability affects Firefox < 60.

If a malicious attacker has used another vulnerability to gain full control over a content process, they may be able to replace the alternate data resources stored in the JavaScript Start-up Bytecode Cache (JSBC) for other JavaScript code. If the parent process then runs this replaced code, the executed script would be run with the parent process’ privileges, escaping the sandbox on content processes. This vulnerability affects Firefox < 60.

Plaintext of decrypted emails can leak through the src attribute of remote images, or links. This vulnerability affects Thunderbird ESR < 52.8 and Thunderbird < 52.8.

Crafted message headers can cause a Thunderbird process to hang on receiving the message. This vulnerability affects Thunderbird ESR < 52.8 and Thunderbird < 52.8.

WebRTC can use a “WrappedI420Buffer” pixel buffer but the owning image object can be freed while it is still in use. This can result in the WebRTC encoder using uninitialized memory, leading to a potentially exploitable crash. This vulnerability affects Firefox < 60.

An integer overflow can occur in the Skia library due to 32-bit integer use in an array without integer overflow checks, resulting in possible out-of-bounds writes. This could lead to a potentially exploitable crash triggerable by web content. This vulnerability affects Thunderbird < 52.8, Thunderbird ESR < 52.8, Firefox < 60, and Firefox ESR < 52.8.