[tor-packagers] New Tor *security* releases: 0.3.5.15, 0.4.4.9, 0.4.5.9, 0.4.6.5

[Nick Mathewson]

Hello!

There are new security releases today.  These releases fix four security
issues discovered by Jann Horn and Sergei Glazunov at Google's Project Zero.

You can find these releases in the usual place at
https://dist.torproject.org.  Make sure (as usual) to check the signatures:
my key is available at
key.cgi?fingerprint=2133BC600AB133E1D826D173FE43009C4607B1FB

Also of note:
   * The 0.4.6.5 release is the first stable release in its series.
   * Tomorrow is end-of-life for the 0.4.4.x series; there will be no more
0.4.4.x releases after today.

For information about how long each series will be supported, see
https://gitlab.torproject.org/tpo/core/team/-/wikis/NetworkTeam/CoreTorReleases
.

The security issues are as follows.  My recommendation is that nobody
should freak out, but everybody should upgrade.

  o Major bugfixes (security):
    - 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):
    - 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):
    - 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.

For complete ChangeLogs for each release, see:

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
https://gitweb.torproject.org/tor.git/tree/ChangeLog?h=tor-0.4.5.9
https://gitweb.torproject.org/tor.git/tree/ChangeLog?h=tor-0.4.6.5

For the ReleaseNotes for the 0.4.6.x series as a whole, see:

https://gitweb.torproject.org/tor.git/tree/ReleaseNotes?h=tor-0.4.6.5

I'll send out announcements after the download page has updated.


best wishes,
-- 
Nick
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