Security

On Thursday Jan 10th we released a Critical Security Update (Synapse 0.34.0.1/0.34.1.1), which fixes a serious security bug in Synapse 0.34.0 and earlier. Many deployments have now upgraded to 0.34.0.1 or 0.34.1.1, and we now consider it appropriate to disclose more information about the issue, to provide context and encourage the remaining affected servers to upgrade as soon as possible.

In Synapse 0.11 (Nov 2015) we added a configuration parameter called “macaroon_secret_key” which relates to our use of macaroons in authentication. Macaroons are authentication tokens which must be signed by the server which generates them, to prevent them being forged by attackers. “macaroon_secret_key” defines the key which is used for this signature, and it must therefore be kept secret to preserve the security of the server.

If the option is not set, Synapse will attempt to derive a secret key from other secrets specified in the configuration file. However, in all versions of Synapse up to and including 0.34.0, this process was faulty and a predictable value was used instead.

So if, your homeserver.yaml does not contain a macaroon_secret_key, you need to upgrade to 0.34.1.1 or 0.34.0.1 or Debian 0.34.0-3~bpo9+2 immediately to prevent the risk of account hijacking.

The vulnerability affects any Synapse installation which does not have a macaroon_secret_key setting. For example, the Debian and Ubuntu packages from Matrix.org, Debian and Ubuntu include a configuration file without an explicit macaroon_secret_key and must upgrade. Anyone who hasn't updated their config since Nov 2015 or who grandfathered their config from the Debian/Ubuntu packages will likely also be affected.

We are not aware of this vulnerability being exploited in the wild, but if you are running an affected server it may still be wise to check your synapse's user_ips database table for any unexpected access to your server's accounts. You could also check your accounts' device lists (shown under Settings in Riot) for unexpected devices, although this is not as reliable as an attacker could cover their tracks to remove unexpected devices.

We'll publish a full post-mortem of the issue once we are confident that most affected servers have been upgraded.

We'd like to apologise for the inconvenience caused by this - especially to folks who upgraded since Friday who were in practice not affected. Due to the nature of the issue we wanted to minimise details about the issue until people had a chance to upgrade. We also did not follow a planned disclosure procedure because Synapse 0.34.1 already unintentionally disclosed the existence of the bug by fixing it (causing the logout bug for affected users which led us to pull the original Synapse 0.34.1 release).

On the plus side, we are approaching the end of beta for Synapse, and going forwards hope to see much better stability and security across the board.

Thanks again for your patience,

The Matrix.org Team

After releasing Synapse v0.34.1, we have become aware of a security vulnerability affecting all previous versions (CVE-2019-5885). v0.34.1 closed the vulnerability but, in some cases, caused users to be logged out of their clients, so we do not recommend v0.34.1 for production use.

Today we release two mitigating versions v0.34.0.1 and v0.34.1.1. Both versions close the vulnerability and will not cause users to be logged out. All installations should be upgraded to one or other immediately.

• Admins who would otherwise upgrade to v0.34.1 (or those that have already done so) should upgrade to v0.34.1.1.
• Admins on v0.34.0, who do not wish to bring in new non-security related behaviour, should upgrade to v0.34.0.1.

You can get the new updates for v0.34.0.1 and v0.34.1.1 here or any of the sources mentioned at https://github.com/matrix-org/synapse. Note, Synapse is now available from PyPI, pick it up here. See also our Synapse installation guide page.

We will publish more details of the vulnerability once admins have had a chance to upgrade. To our knowledge the vulnerability has not been exploited in the wild.

Many thanks for your patience, we are moving ever closer to Synapse reaching v1.0, and fixes like this one edge us ever closer.

Thanks also to the package maintainers who have coordinated with us to ensure distro packages are available for a speedy upgrade!

• Synapse v0.34.0.1 Changelog
• Synapse v0.34.1.1 Changelog

Hi All,

As referenced in yesterday's pre-disclosure, today we are releasing Synapse 0.33.3.1 as a critical security update.

We have patched two security vulnerabilities we identified whilst working on the upcoming r0 spec release for the Server-Server API (see details below). We do not believe either have been exploited in the wild, but strongly recommend everybody running a federated Synapse upgrades immediately.

As always you can get the new update here or from any of the sources mentioned at https://github.com/matrix-org/synapse/

Many thanks for your patience and understanding; with fixes like this we are moving ever closer to Synapse reaching a 1.0 Thanks also to the package maintainers who have coordinated with us to ensure distro packages are available for a speedy upgrade!

Note, for anyone running Debian Jessie, we have prepared a 0.33.2.1 deb (as 0.33.3 dropped support for Jessie).

Synapse 0.33.3.1 (2018-09-06)

SECURITY FIXES

• Fix an issue where event signatures were not always correctly validated (#3796)
• Fix an issue where server_acls could be circumvented for incoming events (#3796)

Internal Changes

• Unignore synctl in .dockerignore to fix docker builds (#3802)

Hi all,

During the ongoing work to finalise a stable release of Matrix's Server-Server federation API, we've been doing a full audit of Synapse's implementation and have identified a serious vulnerability which we are going to release a security update to address (Synapse 0.33.3.1) on Thursday Sept 6th 2018 at 12:00 UTC.

We are coordinating with package maintainers to ensure that patched versions of packages will be available at that time - meanwhile, if you run your own Synapse, please be prepared to upgrade as soon as the patched versions are released.  All previous versions of Synapse are affected, so everyone will want to upgrade.

Thank you for your time, patience and understanding while we resolve the issue,

signed_predisclosure.txt

Hi All,

We have patched two securities vulnerabilities (details follow), we do not believe either have been exploited in the wild, but recommend upgrading asap.

As always you can get the new update from https://github.com/matrix-org/synapse/releases/tag/v0.33.1 or from any of the sources mentioned at https://github.com/matrix-org/synapse/

Thanks

Changes in Synapse v0.33.1 (2018-08-2)

• Fix a potential issue where servers could request events for rooms they have not joined. (#3641)
• Fix a potential issue where users could see events in private rooms before they joined. (#3642)

Folks, Synapse 0.32.0 is an important security update: please upgrade as soon as you can.

The release focuses on security; fixing several federation bugs and adding new features for countering abuse. Notably it includes the ability to blacklist & whitelist servers allowed to send events to a room on a per-room basis via the new m.room.server_acl state event: see MSC1383 for details.  This also closes out https://github.com/matrix-org/matrix-doc/issues/709 - one of our oldest feature requests from users who wish to be able to limit the servers allowed to participate in a given room.

It's important to understand that server ACLs only work if all the servers participating in the room honour them.  In future this will be handled better (as part of ongoing work in making it easier to incrementally version and upgrade the federation protocol).  This means that for the ACLs to work, any servers which don't yet implement ACLs (e.g. older Synapses) have to be ACL'd from the room for the access control to work.   Therefore please upgrade as soon as possible to avoid this problem.

This ongoing flurry of security work is in general all part of moving towards the long-awaited stable release of the Server-Server API. In parallel we've been working on the other main outstanding point: State Resets (i.e. scenarios where you get unexpected results when resolving conflicts between different servers' copies of a room).  There will be a few more major changes and upgrades on the horizon as we fix these, but then we'll finally be able to cut an r0 release of the Server-Server API and Matrix will be one massive step closer to being out of beta!

As always, you can get the new update from https://github.com/matrix-org/synapse/releases/tag/v0.32.1  or any of the sources mentioned at https://github.com/matrix-org/synapse.

Changes in synapse v0.32.0 (2018-07-06)

No changes since 0.32.0rc1

Synapse 0.32.0rc1 (2018-07-05)

Features

• Add blacklist & whitelist of servers allowed to send events to a room via m.room.server_acl event. (merge)
• Cache factor override system for specific caches (#3334)
• Add metrics to track appservice transactions (#3344)
• Try to log more helpful info when a sig verification fails (#3372)
• Synapse now uses the best performing JSON encoder/decoder according to your runtime (simplejson on CPython, stdlib json on PyPy). (#3462)
• Add optional ip_range_whitelist param to AS registration files to lock AS IP access (#3465)
• Reject invalid server names in federation requests (#3480)
• Reject invalid server names in homeserver.yaml (#3483)

Bugfixes

• Strip access_token from outgoing requests (#3327)
• Redact AS tokens in logs (#3349)
• Fix federation backfill from SQLite servers (#3355)
• Fix event-purge-by-ts admin API (#3363)
• Fix event filtering in get_missing_events handler (#3371)
• Synapse is now stricter regarding accepting events which it cannot retrieve the prev_events for. (#3456)
• Fix bug where synapse would explode when receiving unicode in HTTP User-Agent header (#3470)
• Invalidate cache on correct thread to avoid race (#3473)

Improved Documentation

• doc/postgres.rst: fix display of the last command block. Thanks to @ArchangeGabriel! (#3340)

Deprecations and Removals

• Remove was_forgotten_at (#3324)

Misc

• #3332 #3341 #3347 #3348 #3356 #3385 #3446 #3447 #3467 #3474