---
# This file is licensed under the MIT License (MIT) available on
# http://opensource.org/licenses/MIT.
# Text originally from Bitcoin Core project
# Metadata and small formatting changes from Bitcoin.org project

## Please see _releases/0.10.0.md for a release template
required_version: 0.8.4
optional_date: 2013-09-03
title: Bitcoin-Qt version 0.8.4 released
---
Bitcoin-Qt version 0.8.4 is now available from:
  <http://sourceforge.net/projects/bitcoin/files/Bitcoin/bitcoin-0.8.4/>

This is a maintenance release to fix a critical bug and three
security issues; we urge all users to upgrade.

Please report bugs using the issue tracker at github:
  <https://github.com/bitcoin/bitcoin/issues>


How to Upgrade
--------------

If you are running an older version, shut it down. Wait
until it has completely shut down (which might take a few minutes for older
versions), then run the installer (on Windows) or just copy over
/Applications/Bitcoin-Qt (on Mac) or bitcoind/bitcoin-qt (on Linux).

If you are upgrading from version 0.7.2 or earlier, the first time you
run 0.8.4 your blockchain files will be re-indexed, which will take
anywhere from 30 minutes to several hours, depending on the speed of
your machine.

0.8.4 Release notes
===================

Security issues
---------------

An attacker could send a series of messages that resulted in
an integer division-by-zero error in the Bloom Filter handling
code, causing the Bitcoin-Qt or bitcoind process to crash.
Bloom filters were introduced with version 0.8, so versions 0.8.0
through 0.8.3 are vulnerable to this critical denial-of-service attack.

A constant-time algorithm is now used to check RPC password
guess attempts; fixes <https://github.com/bitcoin/bitcoin/issues/2838>
(CVE-2013-4165)

Implement a better fix for the fill-memory-with-orphan-transactions
attack that was fixed in 0.8.3. See
<https://bitslog.wordpress.com/2013/07/18/buggy-cve-2013-4627-patch-open-new-vectors-of-attack/>
for a description of the weaknesses of the previous fix.
(CVE-2013-4627)

Bugs fixed
----------

Fix multi-block reorg transaction resurrection.

Fix non-standard disconnected transactions causing mempool orphans.
This bug could cause nodes running with the -debug flag to crash.

OSX: use `FD_FULLSYNC` with LevelDB, which will (hopefully!)
prevent the database corruption issues many people have
experienced on OSX.

Linux: clicking on bitcoin: links was broken if you were using
a Gnome-based desktop.

Fix a hang-at-shutdown bug that only affects users that compile
their own version of Bitcoin against Boost versions 1.50-1.52.

Other changes
-------------

Checkpoint at block 250,000 to speed up initial block downloads
and make the progress indicator when downloading more accurate.


Thanks to everybody who contributed to the 0.8.4 releases!
----------------------------------------------------------

* Pieter Wuille
* Warren Togami
* Patrick Strateman
* pakt
* Gregory Maxwell
* Sergio Demian Lerner
* grayleonard
* Cory Fields
* Matt Corallo
* Gavin Andresen
