Auth bypass in Element-Hq Synapse
CVE-2024-37303
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.
Vulnerability class: Broken Authentication
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.
EPSS exploit prediction
EPSS: 0.004 (34.8th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 35th percentile — 34.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · 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-gjgr-7834-rhxr (Vendor Advisory)
- github.com/matrix-org/matrix-spec-proposals/pull/3916 (Patch, Issue Tracking)
Frequently asked questions
- What is CVE-2024-37303?
- CVE-2024-37303 is a medium-severity vulnerability in Element-Hq Synapse, classified under Missing Authentication for Critical Function. CVSS score: 5.3/10. Published 2024-12-03.
- How severe is CVE-2024-37303?
- Medium severity. CVSS v3 base score is 5.3 out of 10.