Vulnerability in Matrix Matrix-Rust-Sdk
CVE-2025-66622
matrix-sdk-base is the base component to build a Matrix client library. Versions 0.14.1 and prior are unable to handle responses that include custom m.room.join_rules values due to a serialization bug. This can be exploited to cause a denial-of-service condition, if a user is invited to a room with non-standard join rules, the crate's sync process will stall, preventing further processing for all rooms. This is fixed in version 0.16.0.
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: 0.004 (33.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 33rd percentile — 33.0% 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
- Matrix Matrix-Rust-Sdk
- Matrix-Org Matrix-Rust-Sdk — versions < 0.16.0
Weakness classification (CWE)
References
- github.com/matrix-org/matrix-rust-sdk/security/advisories/GHSA-jj6p-3m75-g2p3 (Patch, Vendor Advisory)
- github.com/matrix-org/matrix-rust-sdk/pull/5924 (Patch, Issue Tracking)
- github.com/matrix-org/matrix-rust-sdk/commit/4ea0418abefab2aa93f8851a4d39c723e7… (Patch)
- rustsec.org/advisories/RUSTSEC-2025-0135.html (Third Party Advisory)
Frequently asked questions
- What is CVE-2025-66622?
- CVE-2025-66622 is a high-severity vulnerability in Matrix Matrix-Rust-Sdk, classified under Improper Handling of Exceptional Conditions. CVSS score: 7.5/10. Published 2025-12-09.
- How severe is CVE-2025-66622?
- High severity. CVSS v3 base score is 7.5 out of 10.