CVE-2024-53867

Synapse Matrix has a partial room state leak via Sliding Sync

MEDIUM
4.3
CVSS Score
Published: December 3, 2024 at 04:52 PM UTC
Updated: June 17, 2026 at 08:09 AM UTC
1 product affected across 1 vendorSynapse

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Severity
MEDIUM4.3
Exploit prediction
EPSS 0.4%
SSVC
No known exploit

Description

Synapse is an open-source Matrix homeserver. The Sliding Sync feature on Synapse versions between 1.113.0rc1 and 1.120.0 can leak partial room state changes to users no longer in a room. Non-state events, like messages, are unaffected. This vulnerability is fixed in 1.120.1.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 1.120.1
Affected range stops below 1.120.1, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

4.3MEDIUMGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-497

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