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CVE-2024-37303

Synapse unauthenticated writes to the media repository allow planting of problematic content

MEDIUM
5.3
CVSS Score
Published: December 3, 2024 at 05:06 PM UTC
Updated: June 17, 2026 at 07:38 AM UTC
2 products affected across 2 vendorsSynapseSynapse

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Severity
MEDIUM5.3
Exploit prediction
EPSS 0.4%
SSVC
No known exploit

Description

Synapse is an open-source Matrix homeserver. Synapse before version 1.106 allows, by design, unauthenticated remote participants to trigger a download and caching of remote media from a remote homeserver to the local media repository. Such content then also becomes available for download from the local homeserver in an unauthenticated way. The implication is that unauthenticated remote adversaries can use this functionality to plant problematic content into the media repository. Synapse 1.106 introduces a partial mitigation in the form of new endpoints which require authentication for media downloads. The unauthenticated endpoints will be frozen in a future release, closing the attack vector.

Affected

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

Synapse· Matrixpypi
95%
v < 1.106.0
Affected range stops below 1.106.0, so it looks safe — our inference, not a vendor statement
Synapse· Element Hq
60%
v < 1.106
Affected range stops below 1.106, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (2)

x_refsource_CONFIRMVendor Advisory
Source: [email protected]
https://github.com/element-hq/synapse/security/advisories/GHSA-gjgr-7834-rhxr
x_refsource_MISCIssue TrackingPatch
Source: [email protected]
https://github.com/matrix-org/matrix-spec-proposals/pull/3916

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

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

CVSS

5.3MEDIUMGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-306

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