XSS in Matrix Synapse
CVE-2021-21333
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 notification emails sent for notification…
EPSS: 0.014 (69.3th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:N.
Affected products
- Matrix Synapse
- Matrix-org Synapse — versions < 1.27.0
- Fedoraproject Fedora — versions 34
Weakness classification (CWE)
References
- security-advisories@github.com (Third Party Advisory, x_refsource_MISC)
- security-advisories@github.com (Patch, Third Party Advisory, x_refsource_MISC)
- security-advisories@github.com (Patch, Third Party Advisory, x_refsource_MISC)
- security-advisories@github.com (x_refsource_CONFIRM, Patch, Third Party Advisory)
- security-advisories@github.com (x_refsource_FEDORA, vendor-advisory)
Frequently asked questions
- What is CVE-2021-21333?
- CVE-2021-21333 is a medium-severity vulnerability in Matrix Synapse, classified under Improper Neutralization of Special Elements in Output Used by a Downstream Component (Injection). CVSS score: 6.1/10. Published 2021-03-26.
- How severe is CVE-2021-21333?
- Medium severity. CVSS v3 base score is 6.1 out of 10.