CVE-2024-36402: Unauthenticated writes to the media repository allow planting of problematic content in Matrix Media Repo
Description
Matrix Media Repo (MMR) is a highly configurable multi-homeserver media repository for Matrix. MMR before version 1.3.5 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. MMR 1.3.5 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. Though extremely limited, server operators can use more strict rate limits based on IP address as a partial workaround.
Classification
CVE ID: CVE-2024-36402
CVSS Base Severity: MEDIUM
CVSS Base Score: 5.3
Affected Products
Vendor: t2bot
Product: matrix-media-repo
Exploit Prediction Scoring System (EPSS)
EPSS Score: 0.04% (probability of being exploited)
EPSS Percentile: 11.64% (scored less or equal to compared to others)
EPSS Date: 2025-02-14 (when was this score calculated)
References
https://github.com/t2bot/matrix-media-repo/security/advisories/GHSA-8vmr-h7h5-cqhghttps://github.com/matrix-org/matrix-spec-proposals/pull/3916