XSS in Matrix Synapse
CVE-2021-21332
Synapse is a Matrix reference homeserver written in python (pypi package matrix-synapse). Matrix is an ecosystem for open federated Instant Messaging and VoIP. In Synapse before version 1.27.0, the password reset endpoint served via Synapse was vulnerable to cross-site scripting (XSS) attacks. The impact depends on the configuration of the domain that Synapse is deployed on, but may allow access to cookies and other browser data, CSRF vulnerabilities, and access to other resources served on the same domain or parent domains. This is fixed in version 1.27.0.
Vulnerability class: XSS (Cross-Site Scripting)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:L/A:N.
EPSS exploit prediction
EPSS: 0.012 (67.5th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 67th percentile — 67.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.012 · newest: 0.012 · change: 0.000
Affected products
- Matrix Synapse
- Matrix-Org Synapse — versions < 1.27.0
- Fedoraproject Fedora — versions 34
Weakness classification (CWE)
References
- github.com/matrix-org/synapse/security/advisories/GHSA-246w-56m2-5899 (Third Party Advisory)
- github.com/matrix-org/synapse/releases/tag/v1.27.0 (Third Party Advisory)
- github.com/matrix-org/synapse/pull/9200 (Patch, Third Party Advisory)
- github.com/matrix-org/synapse/commit/e54746bdf7d5c831eabe4dcea76a7626f1de73df (Patch, Third Party Advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
Frequently asked questions
- What is CVE-2021-21332?
- CVE-2021-21332 is a medium-severity vulnerability in Matrix Synapse, classified under Cross-site Scripting. CVSS score: 6.9/10. Published 2021-03-26.
- How severe is CVE-2021-21332?
- Medium severity. CVSS v3 base score is 6.9 out of 10.