CVE-2022-31152 Synapse vulnerable to denial of service (DoS) due to incorrect application of event authorization rules
Attackers can cause room state divergence and denial of service in Synapse homeservers with federation enabled by exploiting incorrect event authorization rules.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2022-31152?
CVE-2022-31152 is a medium-severity denial of service vulnerability in matrix-org synapse, published on 2 Sep 2022. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. The Matrix specification specifies a list of [event authorization rules](https://spec.matrix.org/v1.2/rooms/v9/#authorization-rules) which must be checked when determining if an event should be accepted into a room. In versions of Synapse up to and including version 1.61.0, some of these rules are not correctly applied. An attacker could craft events which would be accepted by Synapse but not a spec-conformant server, potentially causing divergence in the room state between servers. Administrators of homeservers with federation enabled are advised to upgrade to version 1.62.0 or higher. Federation can be disabled by setting [`federation_domain_whitelist`](https://matrix-org.github.io/synapse/latest/usage/configuration/config_documentation.html#federation_domain_whitelist) to an empty list (`[]`) as a workaround.
Which versions are affected by CVE-2022-31152?
3 open source packages ship an affected version, including matrix-synapse. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
matrix-synapse PyPI | All versions | 1.62.0 |
matrix-synapse PyPI | All versions | 1.62.0rc1 |
matrix-synapse PyPI | All versions | 1.62.0rc1 |
Products include Matrix Synapse.
How do I fix CVE-2022-31152?
Upgrade matrix-synapse to a fixed version for your release line: 1.62.0 or 1.62.0rc1.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2022-31152 being exploited?
There is no known exploitation of CVE-2022-31152 in the wild and no public exploit code.
Other vulnerabilities in matrix-org synapse
- CVE-2019-18835 Improper Verification of Cryptographic Signature in matrix-synapse
- CVE-2024-52815 Synapse allows a a malformed invite to break the invitee's `/sync`
- CVE-2024-52805 Synapse allows unsupported content types to lead to memory exhaustion
- CVE-2024-53863 Synapse can be forced to thumbnail unexpected file formats, invoking external, potentially untrustworthy decoders
- CVE-2024-37302 Synapse denial of service through media disk space consumption
Sources
Also known as GHSA-jhjh-776m-4765, PYSEC-2022-262, UBUNTU-CVE-2022-31152.