Security update for MozillaThunderbird (important)

This update for MozillaThunderbird to version 52.3 fixes security issues
and bugs.

The following vulnerabilities were fixed:

• CVE-2017-7798: XUL injection in the style editor in devtools
• CVE-2017-7800: Use-after-free in WebSockets during disconnection
• CVE-2017-7801: Use-after-free with marquee during window resizing
• CVE-2017-7784: Use-after-free with image observers
• CVE-2017-7802: Use-after-free resizing image elements
• CVE-2017-7785: Buffer overflow manipulating ARIA attributes in DOM
• CVE-2017-7786: Buffer overflow while painting non-displayable SVG
• CVE-2017-7753: Out-of-bounds read with cached style data and
  pseudo-elements#
• CVE-2017-7787: Same-origin policy bypass with iframes through page
  reloads
• CVE-2017-7807: Domain hijacking through AppCache fallback
• CVE-2017-7792: Buffer overflow viewing certificates with an extremely
  long OID
• CVE-2017-7804: Memory protection bypass through WindowsDllDetourPatcher
• CVE-2017-7791: Spoofing following page navigation with data: protocol
  and modal alerts
• CVE-2017-7782: WindowsDllDetourPatcher allocates memory without DEP
  protections
• CVE-2017-7803: CSP containing ‘sandbox’ improperly applied
• CVE-2017-7779: Memory safety bugs fixed in Firefox 55 and Firefox ESR
  52.3

The following bugs were fixed:

• Unwanted inline images shown in rogue SPAM messages
• Deleting message from the POP3 server not working when maildir storage
  was used
• Message disposition flag (replied / forwarded) lost when reply or
  forwarded message was stored as draft and draft was sent later
• Inline images not scaled to fit when printing
• Selected text from another message sometimes included in a reply
• No authorisation prompt displayed when inserting image into email body
  although image URL requires authentication
• Large attachments taking a long time to open under some circumstances