Security update for MozillaThunderbird

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