This update to MozillaThunderbird 51.1.0 fixes security issues and bugs.

In general, these flaws cannot be exploited through email because
scripting is disabled when reading mail, but are potentially
risks in browser or browser-like contexts.

The following vulnerabilities were fixed:
boo#1035082, MFSA 2017-13, boo#1028391, MFSA 2017-09)

- CVE-2017-5443: Out-of-bounds write during BinHex decoding
- CVE-2017-5429: Memory safety bugs fixed in Firefox 53, Firefox ESR 45.9, and Firefox ESR 52.1
- CVE-2017-5464: Memory corruption with accessibility and DOM manipulation
- CVE-2017-5465: Out-of-bounds read in ConvolvePixel
- CVE-2017-5466: Origin confusion when reloading isolated data:text/html URL
- CVE-2017-5467: Memory corruption when drawing Skia content
- CVE-2017-5460: Use-after-free in frame selection
- CVE-2017-5449: Crash during bidirectional unicode manipulation with animation
- CVE-2017-5446: Out-of-bounds read when HTTP/2 DATA frames are sent with incorrect data
- CVE-2017-5447: Out-of-bounds read during glyph processing
- CVE-2017-5444: Buffer overflow while parsing application/http-index-format content
- CVE-2017-5445: Uninitialized values used while parsing application/http-index-format content
- CVE-2017-5442: Use-after-free during style changes
- CVE-2017-5469: Potential Buffer overflow in flex-generated code
- CVE-2017-5440: Use-after-free in txExecutionState destructor during XSLT processing
- CVE-2017-5441: Use-after-free with selection during scroll events
- CVE-2017-5439: Use-after-free in nsTArray Length() during XSLT processing
- CVE-2017-5438: Use-after-free in nsAutoPtr during XSLT processing
- CVE-2017-5437: Vulnerabilities in Libevent library
- CVE-2017-5436: Out-of-bounds write with malicious font in Graphite 2
- CVE-2017-5435: Use-after-free during transaction processing in the editor
- CVE-2017-5434: Use-after-free during focus handling
- CVE-2017-5433: Use-after-free in SMIL animation functions
- CVE-2017-5432: Use-after-free in text input selection
- CVE-2017-5430: Memory safety bugs fixed in Firefox 53 and Firefox ESR 52.1
- CVE-2017-5459: Buffer overflow in WebGL
- CVE-2017-5454; Sandbox escape allowing file system read access through file picker
- CVE-2017-5451: Addressbar spoofing with onblur event
- CVE-2017-5400: asm.js JIT-spray bypass of ASLR and DEP
- CVE-2017-5401: Memory Corruption when handling ErrorResult
- CVE-2017-5402: Use-after-free working with events in FontFace objects
- CVE-2017-5403: Use-after-free using addRange to add range to an incorrect root object
- CVE-2017-5404: Use-after-free working with ranges in selections
- CVE-2017-5406: Segmentation fault in Skia with canvas operations 
- CVE-2017-5407: Pixel and history stealing via floating-point timing side channel with SVG filters
- CVE-2017-5410: Memory corruption during JavaScript garbage collection incremental sweeping
- CVE-2017-5408: Cross-origin reading of video captions in violation of CORS
- CVE-2017-5412: Buffer overflow read in SVG filters
- CVE-2017-5413: Segmentation fault during bidirectional operations
- CVE-2017-5414: File picker can choose incorrect default directory
- CVE-2017-5416: Null dereference crash in HttpChannel
- CVE-2017-5426: Gecko Media Plugin sandbox is not started if seccomp-bpf filter is running
- CVE-2017-5418: Out of bounds read when parsing HTTP digest authorization responses
- CVE-2017-5419: Repeated authentication prompts lead to DOS attack
- CVE-2017-5405: FTP response codes can cause use of uninitialized values for ports
- CVE-2017-5421: Print preview spoofing
- CVE-2017-5422: DOS attack by using view-source: protocol repeatedly in one hyperlink
- CVE-2017-5399: Memory safety bugs fixed in Thunderbird 52
- CVE-2017-5398: Memory safety bugs fixed in Thunderbird 52 and Thunderbird 45.8

The following non-security changes are included:

- Background images not working and other issues related to embedded images when composing email have been fixed
- Google Oauth setup can sometimes not progress to the next step
- Clicking on a link in an email may not open this link in the external browser
- addon blocklist updates
- enable ALSA for systems without PulseAudio
- Optionally remove corresponding data files when removing an account
- Possibility to copy message filter
- Calendar: Event can now be created and edited in a tab
- Calendar: Processing of received invitation counter proposals
- Chat: Support Twitter Direct Messages
- Chat: Liking and favoriting in Twitter
- Chat: Removed Yahoo! Messenger support