CVE-2024-37303Network attack vector

Repository content planting via unauthenticated media caching

Published Dec 3, 2024 · Updated Dec 3, 2024

Missing authentication in media endpoints in Element HQ Synapse before 1.106 allows remote attackers to cache remote content locally. The remote-media download path fetches content from another homeserver, stores it in the local repository, and republishes it without authentication. Any remote participant who can reach the media endpoint can plant attacker-chosen content; the documented consequence is limited to repository integrity.

CVSS severity5.3
Medium
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Missing authentication in media endpoints in Element HQ Synapse before 1.106 allows remote attackers to cache remote content locally. The remote-media download path fetches content from another homeserver, stores it in the local repository, and republishes it without authentication. Any remote participant who can reach the media endpoint can plant attacker-chosen content; the documented consequence is limited to repository integrity.

The record

CVE
CVE-2024-37303
Published
Dec 3, 2024
Updated
Dec 3, 2024
Vendor
Element HQ
Product
Synapse
Classifications
CWE-306, T1565.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 3, 2024CVE publishedPublication date reported by the CVE source.
  2. Dec 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <1.106
  2. Affected versionversion=< 1.106

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Element HQ · Synapseversion=0 <1.106; version=< 1.106

Published CVSS scores

5.3GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-306Missing Authentication for Critical Function
T1565.001Stored Data Manipulation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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