Auth bypass in Matrix Synapse
CVE-2023-42453
Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. Users were able to forge read receipts for any event (if they knew the room ID and event ID). Note that the users were not able to view the events, but simply mark it as read. This could be confusing as clients will show the event as read by the user, even if they are not in the room. This issue has been patched in version 1.93.0. Users are advised to upgrade. There are no known workarounds for this issue.
EPSS: 0.006 (47.5th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 3.1 (Low). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N.
Affected products
- Matrix Synapse
- Matrix-org Synapse — versions >= 0.34.0, < 1.93.0
- Fedoraproject Fedora — versions 37, 38
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Vendor Advisory)
- security-advisories@github.com (Patch, x_refsource_MISC, Issue Tracking)
- security-advisories@github.com (Mailing List, Release Notes)
- security-advisories@github.com (Mailing List, Release Notes)
- security-advisories@github.com
- security-advisories@github.com
Frequently asked questions
- What is CVE-2023-42453?
- CVE-2023-42453 is a low-severity vulnerability in Matrix Synapse, classified under Improper Authorization. CVSS score: 3.1/10. Published 2023-09-27.
- How severe is CVE-2023-42453?
- Low severity. CVSS v3 base score is 3.1 out of 10.