After months of work, we have a new stable release series!
If you build Tor from source, you can download the source
code for 0.4.4.5 on the download page.
Packages should be available within the next several weeks, with a new Tor Browser by some time next week.
Tor 0.4.4.5 is the first stable release in the 0.4.4.x series. This series improves our guard selection algorithms, adds v3 onion balance support, improves the amount of code that can be disabled when running without relay support, and includes numerous small bugfixes and enhancements. It also lays the ground for some IPv6 features that we'll be developing more in the next (0.4.5) series.
Per our support policy, we support each stable release series for nine months after its first stable release, or three months after the first stable release of the next series: whichever is longer. This means that 0.4.4.x will be supported until around June 2021--or later, if 0.4.5.x is later than anticipated.
Note also that support for 0.4.2.x has just ended; support for 0.4.3 will continue until Feb 15, 2021. We still plan to continue supporting 0.3.5.x, our long-term stable series, until Feb 2022.
Below are the changes since 0.4.3.6-rc. For a complete list of changes since 0.4.4.4-rc, see the ChangeLog file.
Changes in version 0.4.4.5 - 2020-09-15
Major features (Proposal 310, performance + security):
Implements Proposal 310, "Bandaid on guard selection". Proposal 310 solves load-balancing issues with older versions of the guard selection algorithm, and improves its security. Under this new algorithm, a newly selected guard never becomes Primary unless all previously sampled guards are unreachable. Implements recommendation from 32088. (Proposal 310 is linked to the CLAPS project researching optimal client location-aware path selections. This project is a collaboration between the UCLouvain Crypto Group, the U.S. Naval Research Laboratory, and Princeton University.)
Major features (fallback directory list):
Replace the 148 fallback directories originally included in Tor 0.4.1.4-rc (of which around 105 are still functional) with a list of 144 fallbacks generated in July 2020. Closes ticket 40061.
There's a new alpha release available for download. If you build Tor from source, you can download the source code for 0.4.4.4-rc from the download page. Packages should be available over the coming weeks, with a new alpha Tor Browser release likely in the coming weeks.
Remember, this is a release candidate, not a a stable release: you should only run this if you'd like to find and report more bugs than usual.
Tor 0.4.4.4-rc is the first release candidate in its series. It fixes several bugs in previous versions, including some that caused annoying behavior for relay and bridge operators.
Changes in version 0.4.4.4-rc - 2020-08-13
Minor features (security):
Channels using obsolete versions of the Tor link protocol are no longer allowed to circumvent address-canonicity checks. (This is only a minor issue, since such channels have no way to set ed25519 keys, and therefore should always be rejected for circuits that specify ed25519 identities.) Closes ticket 40081.
Minor features (defense in depth):
Wipe more data from connection address fields before returning them to the memory heap. Closes ticket 6198.
There's a new alpha release available for download. If you build Tor from source, you can download the source code for 0.4.4.3-alpha from the download page on the website. Packages should be available over the coming weeks, with a new alpha Tor Browser release by mid-August.
Remember, this is an alpha release: you should only run this if you'd like to find and report more bugs than usual.
Tor 0.4.4.3-alpha fixes several annoyances in previous versions, including one affecting NSS users, and several affecting the Linux seccomp2 sandbox.
Changes in version 0.4.4.3-alpha - 2020-07-27
Major features (fallback directory list):
Replace the 148 fallback directories originally included in Tor 0.4.1.4-rc (of which around 105 are still functional) with a list of 144 fallbacks generated in July 2020. Closes ticket 40061.
Major bugfixes (NSS):
When running with NSS enabled, make sure that NSS knows to expect nonblocking sockets. Previously, we set our TCP sockets as nonblocking, but did not tell NSS, which in turn could lead to unexpected blocking behavior. Fixes bug 40035; bugfix on 0.3.5.1-alpha.
There's a new alpha release available for download. If you build Tor from source, you can download the source code for 0.4.4.2-alpha from the download page on the website. Packages should be available over the coming weeks, with a new alpha Tor Browser release around the end of the month.
Remember, this is an alpha release: you should only run this if you'd like to find and report more bugs than usual.
This is the second alpha release in the 0.4.4.x series. It fixes a few bugs in the previous release, and solves a few usability, compatibility, and portability issues.
This release also fixes TROVE-2020-001, a medium-severity denial of service vulnerability affecting all versions of Tor when compiled with the NSS encryption library. (This is not the default configuration.) Using this vulnerability, an attacker could cause an affected Tor instance to crash remotely. This issue is also tracked as CVE-2020- 15572. Anybody running a version of Tor built with the NSS library should upgrade to 0.3.5.11, 0.4.2.8, 0.4.3.6, or 0.4.4.2-alpha or later. If you're running with OpenSSL, this bug doesn't affect your Tor.
Changes in version 0.4.4.2-alpha - 2020-07-09
Major bugfixes (NSS, security):
Fix a crash due to an out-of-bound memory access when Tor is compiled with NSS support. Fixes bug 33119; bugfix on 0.3.5.1-alpha. This issue is also tracked as TROVE-2020-001 and CVE-2020-15572.
Minor features (bootstrap reporting):
Report more detailed reasons for bootstrap failure when the failure happens due to a TLS error. Previously we would just call these errors "MISC" when they happened during read, and "DONE" when they happened during any other TLS operation. Closes ticket 32622.
We have new stable releases today. If you build Tor from source, you can download the source code for 0.4.3.6 on the website. Packages should be available within the next several weeks, with a new Tor Browser by the end of the month.
There are also updated versions for older supported series. You can download 0.3.5.11 and 0.4.2.8 at https://dist.torproject.org/.
These releases fix TROVE-2020-001, a medium-severity denial of service vulnerability affecting all versions of Tor when compiled with the NSS encryption library. (This is not the default configuration.) Using this vulnerability, an attacker could cause an affected Tor instance to crash remotely. This issue is also tracked as CVE-2020- 15572. Anybody running a version of Tor built with the NSS library should upgrade to 0.3.5.11, 0.4.2.8, 0.4.3.6, or 0.4.4.2-alpha or later. (If you are running a version of Tor built with OpenSSL, this bug does not affect your installation.)
Tor 0.4.3.6 backports several bugfixes from later releases, including some affecting usability. Below are the changes in 0.4.3.6. You can also read the changes in 0.3.5.11 and the changes in 0.4.2.8.
Changes in version 0.4.3.6 - 2020-07-09
Major bugfixes (NSS, security, backport from 0.4.4.2-alpha):
Fix a crash due to an out-of-bound memory access when Tor is compiled with NSS support. Fixes bug 33119; bugfix on 0.3.5.1-alpha. This issue is also tracked as TROVE-2020-001 and CVE-2020-15572.
Minor bugfix (CI, Windows, backport from 0.4.4.2-alpha):
Use the correct 64-bit printf format when compiling with MINGW on Appveyor. Fixes bug 40026; bugfix on 0.3.5.5-alpha.
There's a new alpha release available for download. If you build Tor from source, you can download the source code for 0.4.4.1-alpha from the download page. Packages should be available over the coming weeks, with a new alpha Tor Browser release by early July.
Remember, this is an alpha release: you should only run this if you'd like to find and report more bugs than usual.
This is the first alpha release in the 0.4.4.x series. It improves our guard selection algorithms, improves the amount of code that can be disabled when running without relay support, and includes numerous small bugfixes and enhancements. It also lays the ground for some IPv6 features that we'll be developing more in the next (0.4.5) series.
Here are the changes since 0.4.3.5.
Changes in version 0.4.4.1-alpha - 2020-06-16
Major features (Proposal 310, performance + security):
Implements Proposal 310, "Bandaid on guard selection". Proposal 310 solves load-balancing issues with older versions of the guard selection algorithm, and improves its security. Under this new algorithm, a newly selected guard never becomes Primary unless all previously sampled guards are unreachable. Implements recommendation from 32088. (Proposal 310 is linked to the CLAPS project researching optimal client location-aware path selections. This project is a collaboration between the UCLouvain Crypto Group, the U.S. Naval Research Laboratory, and Princeton University.)
Major features (IPv6, relay):
Consider IPv6-only EXTEND2 cells valid on relays. Log a protocol warning if the IPv4 or IPv6 address is an internal address, and internal addresses are not allowed. But continue to use the other address, if it is valid. Closes ticket 33817.
If a relay can extend over IPv4 and IPv6, and both addresses are provided, it chooses between them uniformly at random. Closes ticket 33817.
Re-use existing IPv6 connections for circuit extends. Closes ticket 33817.
Relays may extend circuits over IPv6, if the relay has an IPv6 ORPort, and the client supplies the other relay's IPv6 ORPort in the EXTEND2 cell. IPv6 extends will be used by the relay IPv6 ORPort self-tests in 33222. Closes ticket 33817.
There's a new alpha release available for download. If you build Tor from source, you can download the source code for 0.4.3.4-rc from the download page on the website. Packages should be available over the coming weeks, with a new alpha Tor Browser release likely later this week.
This is a release candidate: unless we find new significant bugs in it, the stable release for the 0.4.3.x series will be substantially the same as this release.
Tor 0.4.3.4-rc is the first release candidate in its series. It fixes several bugs from earlier versions, including one affecting DoS defenses on bridges using pluggable transports.
Changes in version 0.4.3.4-rc - 2020-04-13
Major bugfixes (DoS defenses, bridges, pluggable transport):
Fix a bug that was preventing DoS defenses from running on bridges with a pluggable transport. Previously, the DoS subsystem was not given the transport name of the client connection, thus failed to find the GeoIP cache entry for that client address. Fixes bug 33491; bugfix on 0.3.3.2-alpha.
Minor feature (sendme, flow control):
Default to sending SENDME version 1 cells. (Clients are already sending these, because of a consensus parameter telling them to do so: this change only affects what clients would do if the consensus didn't contain a recommendation.) Closes ticket 33623.
There's a new alpha release available for download. If you build Tor from source, you can download the source code for 0.4.3.3-alpha from the download page on the website. Packages should be available over the coming days, including a new alpha Tor Browser.
Remember, this is an alpha release: you should only run this if you'd like to find and report more bugs than usual.
Tor 0.4.3.3-alpha fixes several bugs in previous releases, including TROVE-2020-002, a major denial-of-service vulnerability that affected all released Tor instances since 0.2.1.5-alpha. Using this vulnerability, an attacker could cause Tor instances to consume a huge amount of CPU, disrupting their operations for several seconds or minutes. This attack could be launched by anybody against a relay, or by a directory cache against any client that had connected to it. The attacker could launch this attack as much as they wanted, thereby disrupting service or creating patterns that could aid in traffic analysis. This issue was found by OSS-Fuzz, and is also tracked as CVE-2020-10592.
We do not have reason to believe that this attack is currently being exploited in the wild, but nonetheless we advise everyone to upgrade as soon as packages are available.
There are also new stable releases coming out today; I'll describe them in an upcoming post.
Changes in version 0.4.3.3-alpha - 2020-03-18
Major bugfixes (security, denial-of-service):
Fix a denial-of-service bug that could be used by anyone to consume a bunch of CPU on any Tor relay or authority, or by directories to consume a bunch of CPU on clients or hidden services. Because of the potential for CPU consumption to introduce observable timing patterns, we are treating this as a high-severity security issue. Fixes bug 33119; bugfix on 0.2.1.5-alpha. Found by OSS-Fuzz. We are also tracking this issue as TROVE-2020-002 and CVE-2020-10592.
Major bugfixes (circuit padding, memory leak):
Avoid a remotely triggered memory leak in the case that a circuit padding machine is somehow negotiated twice on the same circuit. Fixes bug 33619; bugfix on 0.4.0.1-alpha. Found by Tobias Pulls. This is also tracked as TROVE-2020-004 and CVE-2020-10593.
We have new releases today. If you build Tor from source, you can download the source code for 0.4.2.7 from the download page on the website. Packages should be available within the next several days, including a new Tor Browser.
