What’s Vulnerable › Vulnerabilities
CVE-2024-37302: Synapse denial of service through media disk space consumption
- Severity: high (CVSS 7.5 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.6% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2024-12-03 · updated 2026-06-17
- Weakness: CWE-770
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.
Affected products
- matrix-org synapse: before 1.106.0 — fixed in 1.106.0
How to fix
Upgrade to a fixed version: matrix-org synapse 1.106.0. Check the vendor advisory for mitigations.
References
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