This update for MozillaThunderbird  to version 52.6 fixes several issues.

These security issues were fixed:

- CVE-2018-5095: Integer overflow in Skia library during edge builder
  allocation (bsc#1077291).
- CVE-2018-5096: Use-after-free while editing form elements (bsc#1077291).
- CVE-2018-5097: Use-after-free when source document is manipulated during XSLT
  (bsc#1077291).
- CVE-2018-5098: Use-after-free while manipulating form input elements
  (bsc#1077291).
- CVE-2018-5099: Use-after-free with widget listener (bsc#1077291).
- CVE-2018-5102: Use-after-free in HTML media elements (bsc#1077291).
- CVE-2018-5103: Use-after-free during mouse event handling (bsc#1077291).
- CVE-2018-5104: Use-after-free during font face manipulation (bsc#1077291).
- CVE-2018-5117: URL spoofing with right-to-left text aligned left-to-right
  (bsc#1077291).
- CVE-2018-5089: Various memory safety bugs (bsc#1077291).

These security issues were fixed:

- Searching message bodies of messages in local folders, including
  filter and quick filter operations, not working reliably: Content
  not found in base64-encode message parts, non-ASCII text not found
  and false positives found.
- Defective messages (without at least one expected header) not shown
  in IMAP folders but shown on mobile devices
- Calendar: Unintended task deletion if numlock is enabled