DC++ 0.868 is out and marked as stable

A year after the previous version, DC++ 0.868 is now available with various library updates (notably OpenSSL 1.1.1 with TLS 1.3 support) and a revised selection of public hub lists.

The list of public hubs came with the client has been pretty much outdated for some time. A few previously listed servers are already defunct while some are changed their web addresses. Therefore a refreshed list of secure and working hublist servers was long overdue. Many of such new public hublists will get auto-added to your collection upon the update to version 0.868 due to a change of policy regarding hublist server defaults. In the past a change of default hublist servers were not reflected in the actual settings – you had to remove  all existing server entries manually to get the updated defaults. This method, being deemed a bit cumbersome, has changed; in this release the addition will happen automatically and it will be the same in case of any future changes as well. A “Reset hub lists” button is also available in the settings should you want to quickly clean up the list of servers and get back to the defaults.

With the OpenSSL library update, DC++ 0.868 introduces support for TLS version 1.3 and is automatically preferring this newest secure communication standard when connecting to other DC clients and hubs. Backwards compatibility to the earlier versions of the protocol is decided to be maintained, similarly to most of the modern popular web browser software, until at least 2020.

Above the aforemntioned feature updates this is a maintanence release, with a few small updates here and there. There’s also a feature removal: support for the long defunct (and often criticised) Coral CDN network ended with this version.

Due to the useful features and security related fixes an immediate upgrade from earlier versions of DC++ is highly recommended.


DC++ 0.867 is out – Vulnerability disclosure

DC++ 0.867 has been released and also marked as the stable release. It fixes a serious remotely exploitable vulnerability that would crash the client if a malicious attacker sends trivially compilable malformed search result messages.

The victim should not need to initiate searches and the attacker should not need to be logged on to a hub for a successful exploitation altough the obvious place for finding victims and collecting attack surface information are the DC hubs.

Clients configured to a working active connectivity mode are the easiest targets, especially when logged in to any kind of Direct Connect hubs. Theoretically exploits can be created for clients running in passive mode, too, using possible additional weaknesses in various hub software.

The vulnerability seems to be exist as far back as in version 0.671 (released in 2005) and in all newer releases up to DC++ 0.866. Many other DC clients based on dclib, the core library of DC++ and released over the last 12 years should be vulnerable, too.

The vulnerability report and detalis are now publicly available in the DC++ bug tracker. Updating and using the newest, most secure DC clients has never been more important so the best everyone can do is to head over the DC++ download page and upgrade as soon as possible.

DC++ 0.866

DC++ 0.866 is out. This release fixes a serious issue that allows remote denial of service attacks (ability to freeze the client remotely by any user of the connected hubs).  Besides the hardened security, version 0.866 also improves UPnP port mapping which might fix certain issues with the automatic connectivity setup.

The details of the vulnerability will be disclosed as soon as 0.866 or any forthcoming DC++ release is marked as stable.

DC++ 0.865 is out and marked as stable

DC++ 0.865 has been released with zlib and OpenSSL libraries have been updated. The compression issue found in the previous version has been fixed therefore upgrading to version 0.865 is highly recommended.

DC++ 0.864

DC++ 0.864, along with changes in share filtering and an addition of testing notifications, fixes a stability issue regarding processing of search results. The issue is introduced in the previous release so immediate upgrade for users running version 0.863 is highly recommended.


Tests with the 0.864 version of DC++ have uncovered a transfer issue (see https://bugs.launchpad.net/dcplusplus/+bug/1656050) so the release has been removed. It never made it to the “stable” status.

Please keep using version 0.863 for now.

DC++ 0.863

DC++ 0.863, along with minor changes, fixes a stability issue in the 32-bit builds. Furthermore it contains additional optimizations for the benefit of users running DC++ on 32-bit operating systems. DC++ needs SSE3 support from this release on which means it requires Intel Core or AMD A64 X2 or newer CPUs to run. Some steppings of older processors will still work though.

Immediate upgrade for users running 32-bit operating systems is highly recommended.

DC++ 0.861

The first new DC++ release in more than a year, version 0.861, brings plenty of enhancements and security updates. The following are the list of key fixes and improvements over version 0.851:

  • Just like as in the previous major release, version 0.850, there are new functions that has been requested by the users through the bug tracker. Such features are an option for autostart DC++ when Windows starts, quick-check hubs with encrypted connections in Search frame, search capability in the Notepad window, hub connectivity status icon in the public hub list and a text encoding setting for favorite NMDC hubs.
  • We’ve improved Windows 10 compatibility by fixing a visual bug in the chat and updating the UPnP mapper. The latter may fix reported issues with automatic connectivity setup under Windows 10.
  • Added an icon toolbar to the Download queue to make the control of the downloads and priorities easier.
  • Fixed security issues related to OpenSSL and also problems with keyprint validation and secure transfers.
  • As like any program that displays clickable links from outside sources should do, now DC++ also introduces a whitelist of URIs that it allows to be directly opened without an user prompt. It means that a confirmation dialog will appear before the actual opening of any type of links that’s not whitelisted. This prevents accidental launching of any 3rd party software that is registered to certain URIs in the system and might be used to exploit existing vulnerabilities or execute arbitrary code. The URI whitelist is freely configurable in the settings dialog. We’d like to thank Kacper Rybczynski for pointing out this issue and for working with us to help protect DC++ users.
  • There’s a new structure for manual connectivity settings and lots of new options available to fine tune IPv6 connectivity. The automatic connectivity setup now enables IPv6 connectivity if the bound network interface is assigned with a public v6 IP address. Note that all parts of the IPv6 connectivity is in an early beta stage and prone to failures and that v6 connections are only supported to ADC hubs and between ADC hub users.
  • With version 0.860, DC++ has ended Windows XP support and requires Windows Vista as a minimum Windows version to run. This has enabled a lot of cleaning in the code which also results performance improvements.
  • Version 0.861 introduces more significant performance improvements by being compiled with the latest MinGW technology as well as by requiring SSE2 CPU support. The latter brings extra preformance boost to 32-bit builds of DC++ in several areas, notably in the speed of hashing, download queue matching and respond to searches. This also means that DC++ requires Intel Pentium 4 / AMD Athlon64 or newer processors from now.

The list of complete changes with links to the discussions in the bug tracker are available here. Due to the nature of fixes an immediate upgrade from earlier versions of DC++ is highly recommended.