Security vulnerabilities fixed in Thunderbird 52.8 — Mozilla

Mozilla developers backported selected changes in the Skia library. These changes correct memory corruption issues including invalid buffer reads and writes during graphic operations.
Using remote content in encrypted messages can lead to the disclosure of plaintext.
A use-after-free vulnerability can occur while enumerating attributes during SVG animations with clip paths. This results in a potentially exploitable crash.
A use-after-free vulnerability can occur while adjusting layout during SVG animations with text paths. This results in a potentially exploitable crash.
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.
Crafted message headers can cause a Thunderbird process to hang on receiving the message.
Plaintext of decrypted emails can leak through the src attribute of remote images, or links.
It is possible to spoof the filename of an attachment and display an arbitrary attachment name. This could lead to a user opening a remote attachment which is a different file type than expected.
Sites can bypass security checks on permissions to install lightweight themes by manipulating the baseURI property of the theme element. This could allow a malicious site to install a theme without user interaction which could contain offensive or embarrassing images.
In the Windows 10 April 2018 Update, Windows Defender SmartScreen honors the SEE_MASK_FLAG_NO_UI flag associated with downloaded files and will not show any UI. Files that are unknown and potentially dangerous will be allowed to run because SmartScreen will not prompt the user for a decision, and if the user is offline all files will be allowed to be opened because Windows won’t prompt the user to ask what to do. Firefox incorrectly sets this flag when downloading files, leading to less secure behavior from SmartScreen. Note: this issue only affects Windows 10 users running the April 2018 update or later. It does not affect other Windows users or other operating systems.
A buffer overflow was found during UTF8 to Unicode string conversion within JavaScript with extremely large amounts of data. This vulnerability requires the use of a malicious or vulnerable legacy extension in order to occur.
Plaintext of decrypted emails can leak through by user submitting an embedded form.
Mozilla developers and community members Christoph Diehl, Randell Jesup, Tyson Smith, Alex Gaynor, Ronald Crane, Julian Hector, Kannan Vijayan, and Jason Kratzer reported memory safety bugs present in Firefox 59, Firefox ESR 52.7, and Thunderbird 52.7. Some of these bugs showed evidence of memory corruption and we presume that with enough effort that some of these could be exploited to run arbitrary code.