Incorrect authorization in Synapse - CVE-2022-39374
Published: May 24, 2023 / Updated: May 4, 2026
Vulnerability identifier: #VU129606
CSH Severity: Low
CVSS v4: 7.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2022-39374
CWE-ID: CWE-863
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
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.
Affected software
Synapse
Fedora
rust-pythonize
python-matrix-common
matrix-synapse
Fedora
rust-pythonize
python-matrix-common
matrix-synapse
How to mitigate CVE-2022-39374
Install security update from vendor's website.
Synapse - update to 1.68.0
rust-pythonize - update to 0.19.0-1.fc37
python-matrix-common - update to 1.3.0-7.fc37
matrix-synapse - update to 1.80.0-5.fc37
rust-pythonize - update to 0.19.0-1.fc37
python-matrix-common - update to 1.3.0-7.fc37
matrix-synapse - update to 1.80.0-5.fc37