CVE-2023-43796 - CVE House
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Status published Medium CVE-2023-43796

Synapse vulnerable to leak of remote user device information

Vulnerability Description

Synapse is an open-source Matrix homeserver Prior to versions 1.95.1 and 1.96.0rc1, cached device information of remote users can be queried from Synapse. This can be used to enumerate the remote users known to a homeserver. System administrators are encouraged to upgrade to Synapse 1.95.1 or 1.96.0rc1 to receive a patch. As a workaround, the `federation_domain_whitelist` can be used to limit federation traffic with a homeserver.

Impact Analysis

Refer to official advisory for detailed impact metrics.

Remediation

Ensure systems are updated to the latest vendor-supplied patch levels.

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Credits & Attribution

No credits recorded in the NVD database.

References

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Affected Vendor

Affected Software

synapse
Vulnerable Versions:
< 1.95.1

Timeline

Official Publish: October 31st, 2023
Last Modified: February 13th, 2025
Added to House: July 22nd, 2026

CVSS Vectors

V3: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Weaknesses (CWE)

CWE-200

MITRE ATT&CK TTPs

T1213 Data from Information Repositories
Collection
T1005 Data from Local System
Collection
T1552 Unsecured Credentials
Credential Access
T1041 Exfiltration Over C2 Channel
Exfiltration