CVE-2024-37302

Synapse denial of service through media disk space consumption

Published Dec 3, 2024 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
Description
Synapse is an open-source Matrix homeserver. Synapse versions before 1.106 are vulnerable to a disk fill attack, where an unauthenticated adversary can induce Synapse to download and cache large amounts of remote media. The default rate limit strategy is insufficient to mitigate this. This can lead to a denial of service, ranging from further media uploads/downloads failing to completely unavailability of the Synapse process, depending on how Synapse was deployed. Synapse 1.106 introduces a new "leaky bucket" rate limit on remote media downloads to reduce the amount of data a user can request at a time. This does not fully address the issue, but does limit an unauthenticated user's ability to request large amounts of data to be cached.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
EUVD EUVD EUVD-2024-3424 Synapse is an open-source Matrix homeserver. Synapse versions before 1.106 are vulnerable to a disk fill attack, where an unauthenticated adversary can induce Synapse to download and cache large amounts of remote media. The default rate limit strategy is insufficient to mitigate this. This can lead to a denial of service, ranging from further media uploads/downloads failing to completely unavailability of the Synapse process, depending on how Synapse was deployed. Synapse 1.106 introduces a new "leaky bucket" rate limit on remote media downloads to reduce the amount of data a user can request at a time. This does not fully address the issue, but does limit an unauthenticated user's ability to request large amounts of data to be cached.
Github GHSA Github GHSA GHSA-4mhg-xv73-xq2x Synapse denial of service through media disk space consumption
History
Type Values Removed Values Added
First Time appeared Matrix
Matrix synapse
CPEs cpe:2.3:a:matrix:synapse:*:*:*:*:*:*:*:*
Vendors & Products Matrix
Matrix synapse
Type Values Removed Values Added
First Time appeared Element-hq
Element-hq synapse
CPEs cpe:2.3:a:element-hq:synapse:*:*:*:*:*:*:*:*
Vendors & Products Element-hq
Element-hq synapse
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description Synapse is an open-source Matrix homeserver. Synapse versions before 1.106 are vulnerable to a disk fill attack, where an unauthenticated adversary can induce Synapse to download and cache large amounts of remote media. The default rate limit strategy is insufficient to mitigate this. This can lead to a denial of service, ranging from further media uploads/downloads failing to completely unavailability of the Synapse process, depending on how Synapse was deployed. Synapse 1.106 introduces a new "leaky bucket" rate limit on remote media downloads to reduce the amount of data a user can request at a time. This does not fully address the issue, but does limit an unauthenticated user's ability to request large amounts of data to be cached.
Title Synapse denial of service through media disk space consumption
Weaknesses CWE-770
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Dec 3, 2024, 6:56 PM
Reserved
Jun 5, 2024, 8:10 PM
Status
Analyzed
Published
Dec 3, 2024, 5:15 PM
Modified
Jun 17, 2026, 7:38 AM