Hello, everyone!

(If you are about to reply saying "please take me off this list", instead please follow these instructions: https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-announce/ . If you have trouble, it is probably because you subscribed using a different address than the one you are trying to unsubscribe with. You will have to enter the actual email address you used when you subscribed.) Source code for Tor 0.3.5.15, 0.4.4.9, and 0.4.5.9 is now available; since these are older release series, you can download the source code at https://dist.torproject.org/ . Packages should be available within the next several weeks, with a new Tor Browser around the end of the week.

This release fixes several security vulnerabilities, described in the changelogs. We are also releasing security fixes for the other supported release series; I'll describe them in a separate email. I recommend that everybody upgrade to 0.3.5.15, 0.4.4.9, 0.4.5.9, or 0.4.6.5 as soon as binaries are available (or right now, if you build from source).

Below is the changelog for 0.4.5.9. You can find the changelogs for the other releases at: https://gitweb.torproject.org/tor.git/tree/ChangeLog?h=tor-0.3.5.15 https://gitweb.torproject.org/tor.git/tree/ChangeLog?h=tor-0.4.4.9

Changes in version 0.4.5.9 - 2021-06-14 Tor 0.4.5.9 fixes several security issues, including a denial-of-service attack against onion service clients, and another denial-of-service attack against relays. Everybody should upgrade to one of 0.3.5.15, 0.4.4.9, 0.4.5.9, or 0.4.6.5.

o Major bugfixes (security, backport from 0.4.6.5): - Don't allow relays to spoof RELAY_END or RELAY_RESOLVED cell on half-closed streams. Previously, clients failed to validate which hop sent these cells: this would allow a relay on a circuit to end a stream that wasn't actually built with it. Fixes bug 40389; bugfix on 0.3.5.1-alpha. This issue is also tracked as TROVE-2021- 003 and CVE-2021-34548.

o Major bugfixes (security, defense-in-depth, backport from 0.4.6.5): - Detect more failure conditions from the OpenSSL RNG code. Previously, we would detect errors from a missing RNG implementation, but not failures from the RNG code itself. Fortunately, it appears those failures do not happen in practice when Tor is using OpenSSL's default RNG implementation. Fixes bug 40390; bugfix on 0.2.8.1-alpha. This issue is also tracked as TROVE-2021-004. Reported by Jann Horn at Google's Project Zero.

o Major bugfixes (security, denial of service, backport from 0.4.6.5): - Resist a hashtable-based CPU denial-of-service attack against relays. Previously we used a naive unkeyed hash function to look up circuits in a circuitmux object. An attacker could exploit this to construct circuits with chosen circuit IDs, to create collisions and make the hash table inefficient. Now we use a SipHash construction here instead. Fixes bug 40391; bugfix on 0.2.4.4-alpha. This issue is also tracked as TROVE-2021-005 and CVE-2021-34549. Reported by Jann Horn from Google's Project Zero. - Fix an out-of-bounds memory access in v3 onion service descriptor parsing. An attacker could exploit this bug by crafting an onion service descriptor that would crash any client that tried to visit it. Fixes bug 40392; bugfix on 0.3.0.1-alpha. This issue is also tracked as TROVE-2021-006 and CVE-2021-34550. Reported by Sergei Glazunov from Google's Project Zero.

o Minor features (compatibility, backport from 0.4.6.4-rc): - Remove an assertion function related to TLS renegotiation. It was used nowhere outside the unit tests, and it was breaking compilation with recent alpha releases of OpenSSL 3.0.0. Closes ticket 40399.

o Minor features (geoip data): - Update the geoip files to match the IPFire Location Database, as retrieved on 2021/06/10.

o Minor bugfixes (control, sandbox, backport from 0.4.6.4-rc): - Allow the control command SAVECONF to succeed when the seccomp sandbox is enabled, and make SAVECONF keep only one backup file to simplify implementation. Previously SAVECONF allowed a large number of backup files, which made it incompatible with the sandbox. Fixes bug 40317; bugfix on 0.2.5.4-alpha. Patch by Daniel Pinto.

o Minor bugfixes (metrics port, backport from 0.4.6.4-rc): - Fix a bug that made tor try to re-bind() on an already open MetricsPort every 60 seconds. Fixes bug 40370; bugfix on 0.4.5.1-alpha.