Security update for Mozilla Thunderbird (important)

This update for Mozilla Thunderbird to version 52.8 fixes the following
issues:

Security issues fixed (MFSA 2018-13, boo#1092548):

• CVE-2018-5183: Backport critical security fixes in Skia
• CVE-2018-5154: Use-after-free with SVG animations and clip paths
• CVE-2018-5155: Use-after-free with SVG animations and text paths
• CVE-2018-5159: Integer overflow and out-of-bounds write in Skia
• CVE-2018-5168: Lightweight themes can be installed without user
  interaction
• CVE-2018-5178: Buffer overflow during UTF-8 to Unicode string conversion
  through legacy extension
• CVE-2018-5150: Memory safety bugs fixed in Firefox 60, Firefox ESR 52.8,
  and Thunderbird 52.8
• CVE-2018-5161: Hang via malformed headers (bsc#1093970)
• CVE-2018-5162: Encrypted mail leaks plaintext through src attribute
  (bsc#1093971)
• CVE-2018-5170: Filename spoofing for external attachments (bsc#1093972)
• CVE-2018-5184: Full plaintext recovery in S/MIME via chosen-ciphertext
  attack (bsc#1093969)
• CVE-2018-5185: Leaking plaintext through HTML forms (bsc#1093973)