Resource exhaustion in Element-Hq Synapse
CVE-2024-37302
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.006 (46.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 46th percentile — 46.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: +0.000
Affected products
- Element-Hq Synapse — versions < 1.106
- Matrix Synapse
Weakness classification (CWE)
References
- github.com/element-hq/synapse/security/advisories/GHSA-4mhg-xv73-xq2x (Vendor Advisory)
Frequently asked questions
- What is CVE-2024-37302?
- CVE-2024-37302 is a high-severity vulnerability in Element-Hq Synapse, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 7.5/10. Published 2024-12-03.
- How severe is CVE-2024-37302?
- High severity. CVSS v3 base score is 7.5 out of 10.