HOMEVULNERABILITIESCVE-2023-43796
MEDIUM

CVE-2023-43796

CWE-200Published: October 31, 2023· Updated: Jun 17, 2026

5.3
CVSS v3.1

Official 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.

NVD Source

Technical Analysis

CVE-2023-43796 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

From a weakness classification perspective (CWE-200): Information exposure vulnerabilities leak sensitive data to unauthorized actors.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityLow
IntegrityNone
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Affected Vendors & Products

Fedora1 product(s)
fedora
matrix1 product(s)
synapse
Source: NVD CPE · 3 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://github.com/matrix-org/synapse/commit/daec55e1fe120c564240c5386e77941372bf458f
PATCHhttps://github.com/matrix-org/synapse/commit/daec55e1fe120c564240c5386e77941372bf458f
ADVISORYhttps://github.com/matrix-org/synapse/security/advisories/GHSA-mp92-3jfm-3575
ADVISORYhttps://github.com/matrix-org/synapse/security/advisories/GHSA-mp92-3jfm-3575

All References (10)

→
https://github.com/matrix-org/synapse/commit/daec55e1fe120c564240c5386e77941372bf458fPatch
→
https://github.com/matrix-org/synapse/security/advisories/GHSA-mp92-3jfm-3575Vendor Advisory
→
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/2IDEEZMFJBDLTFHQUTZRJJNCOZGQ2ZVS/Mailing List
→
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/VH3RNC5ZPQZ4OKPSL4E6BBJSZOQLGDEY/Mailing List
→
https://security.gentoo.org/glsa/202401-12
→
https://github.com/matrix-org/synapse/commit/daec55e1fe120c564240c5386e77941372bf458fPatch
→
https://github.com/matrix-org/synapse/security/advisories/GHSA-mp92-3jfm-3575Vendor Advisory
→
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/2IDEEZMFJBDLTFHQUTZRJJNCOZGQ2ZVS/Mailing List
→
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/VH3RNC5ZPQZ4OKPSL4E6BBJSZOQLGDEY/Mailing List
→
https://security.gentoo.org/glsa/202401-12

Quick Facts

CVE IDCVE-2023-43796
CVSS Score5.3 / 10
SeverityMEDIUM
WeaknessCWE-200
CISA KEVNo
Affected2 vendor(s)
PublishedOct 31, 2023

Related CVEs (CWE-200)

CVE-2008-0082
10.0
CVE-2008-1155
10.0
CVE-2025-61481
10.0
CVE-2025-22612
10.0
CVE-2026-27604
10.0
CVE-2011-1643
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2023-43796 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWatch. CVE data is provided under the NVD usage policy.
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