SB2023052449 - Incorrect authorization in Synapse
Published: May 24, 2023 Updated: May 4, 2026
Security Bulletin ID
SB2023052449
CSH Severity
Low
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Remote access
Highest impact
Denial of service
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 vulnerability.
1) Incorrect authorization (CVE-ID: CVE-2022-39374)
The vulnerability allows a remote user to cause a denial of service.
The vulnerability exists due to improper authorization in event authorization rules during state resolution when processing room state from a joined malicious homeserver. A remote user can trick Synapse into accepting previously rejected events to cause a denial of service.
Exploitation is possible only when the homeserver is joined to rooms that include or invite members of untrusted homeservers.
Remediation
Install update from vendor's website.