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🛡️ CVE-2022-39374 — matrix-synapse

🟠 CVSS 8.0 — High ✅ No Known Exploit CWE-400 NVD
8.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Synapse Denial of service due to incorrect application of event authorization rules during state resolution

Impact

If Synapse and a malicious homeserver are both joined to the same room, the malicious homeserver can trick Synapse into accepting previously rejected events into its view of the current state of that room. This can be exploited in a way that causes all further messages and state changes sent in that room from the vulnerable homeserver to be rejected.

Synapse homeservers are affected by this issue if and only if they are joined to rooms which members of untrusted homeservers are joined or invited to.

  • Synapse homeservers in rooms available over public federation are affected.
  • Synapse homeservers with federation disabled are not affected.
  • Synapse homeservers in a closed federation containing only trusted servers are not affected.
  • Synapse homeservers which are only joined to rooms with federation disabled[^1] are not affected.

Patches

Administrators of homeservers with federation enabled are advised to upgrade to 1.68.0 or higher.

Workarounds

  • 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 ([]). from the vulnerable homeserver to be rejected. This issue has been patched in version 1.68.0

References

  • https://github.com/matrix-org/synapse/pull/13723

[^1]: See m.federate in the [m.room.create definition](https://spec.matrix.org/v1.4/client-server-api/#mroomcreate).

For more information

If you have any questions or comments about this advisory, e-mail us at [security@matrix.org](mailto:[email protected]).

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: Low — an ordinary user account is enough.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: None.
  • Integrity impact: None.
  • Availability impact: High — total loss, or loss the attacker controls.

Weakness class

CVE-2022-39374 is classified as CWE-400: Uncontrolled Resource Consumption. A request can consume memory, CPU or storage without limit, exhausting capacity for everyone else.

Affected software

CVE-2022-39374 is recorded against 2 packages.

  • matrix-synapse (from 1.62.0 up to 1.68.0rc1)
  • synapse (from 1.62.0 up to 1.68.0)

Timeline and source

Published on 24 May 2023 and last revised on 30 September 2024. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from NVD.

References

github.com (Web)
nvd.nist.gov (Advisory)
github.com (Web)
github.com (Web)
github.com (Package)
github.com (Web)
lists.fedoraproject.org (Web)

Other advisories for this package

matrix-synapse has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-400: Uncontrolled Resource Consumption) in other software:

CVE-2022-39374 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity HIGH
CVSS Score 8.0
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CWE CWE-400
Public Exploit ✅ No
Source NVD
Published 2023-05-24
Updated 2026-08-20
Modified 2024-09-30

Affected Packages

Software From version Fixed in
matrix-synapse 1.62.0 1.68.0rc1
synapse 1.62.0 1.68.0

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