Is CVE-2024-37303 in the CISA KEV catalog?

No. CVE-2024-37303 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2024-37303?

CVE-2024-37303 has a CVSS v3 base score of 5.3 (MEDIUM).

What is the EPSS score for CVE-2024-37303?

CVE-2024-37303 has an EPSS score of 0.42% (34th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2024-37303?

Upgrade matrix-synapse on debian unstable to 1.116.0-1 or later.

CVE & CISA-KEV Catalog

CVE-2024-37303

MEDIUM

5.3

CVSS v3

NVD

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.

CWE-306Missing Authentication for Critical Function

How to fix

Remediation Available

matrix-synapseDebian

Fixed in:1.116.0-1CVE-2024-37303

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityLow

AvailabilityNone

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

Exploit Intelligence

0.42%probability of exploitation in 30 days

34thpercentile

Low risk: more likely to be exploited than 34% of all known CVEs.

References

Patch1

github.com

Vendor Advisory1

github.com

Related Vulnerabilities

Other CWE-306 (Missing Authentication for Critical Function) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2017-10271	High	7.5	100%	KEV + Ransom	-
CVE-2023-42793	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2025-3248	Critical	9.8	100%	KEV	Fix
CVE-2022-1388	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2021-37415	Critical	9.8	100%	KEV	-
CVE-2023-21839	High	7.5	100%	KEV	-

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-08-26.