Synapse vulnerable to leak of remote user device information

Description

Impact

Cached device information of remote users can be queried from Synapse. This can be used to enumerate the remote users known to a homeserver.

Patches

System administrators are encouraged to upgrade to Synapse 1.95.1 as soon as possible.

Workarounds

The federation_domain_whitelist can be used to limit federation traffic with a homeserver.

Basic information

Type
reviewed
Severity
medium
Advisory on GitHub
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Repository advisory
Open repository advisory ↗
Source code
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Published (advisory)
2023-10-31 20:29:49 UTC
Updated
2025-02-13 19:21:03 UTC
GitHub reviewed
2023-10-31 20:29:49 UTC
NVD published
2023-10-31

EPSS Score

Score Percentile
0.24% 46.93%

CVSS Scores

Base score Version Severity Vector
5.3 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.

Identifiers

CWEs

CWE id Name
CWE-200 Exposure of Sensitive Information to an Unauthorized Actor

Affected packages (1)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem Package Vulnerable range First patched Vulnerable functions
pip matrix-synapse < 1.95.1 1.95.1

References

cvelogic Threat Intelligence