CVE-2022-31152

Synapse vulnerable to denial of service (DoS) due to incorrect application of event authorization rules

HIGH
7.5
CVSS Score
Published: September 2, 2022 at 08:00 PM UTC
Updated: June 17, 2026 at 04:44 AM UTC
2 products affected across 2 vendorsSynapseSynapse

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Severity
HIGH7.5
Exploit prediction
EPSS 1%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 1.62.0
Affected range stops below 1.62.0, so it looks safe — our inference, not a vendor statement
v < 1.62.0
Affected range stops below 1.62.0, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (4)

x_refsource_MISCIssue TrackingPatchThird Party Advisory
https://github.com/matrix-org/synapse/pull/13087
x_refsource_MISCIssue TrackingPatchThird Party Advisory
https://github.com/matrix-org/synapse/pull/13088
x_refsource_MISCRelease NotesThird Party Advisory
https://github.com/matrix-org/synapse/releases/tag/v1.62.0
x_refsource_CONFIRMIssue TrackingMitigationThird Party Advisory
https://github.com/matrix-org/synapse/security/advisories/GHSA-jhjh-776m-4765

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-703CWE-755

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