XSS in Matrix Synapse
CVE-2020-26257
Matrix is an ecosystem for open federated Instant Messaging and VoIP. Synapse is a reference "homeserver" implementation of Matrix. A malicious or poorly-implemented homeserver can inject malformed events into a room by specifying a differ…
Vulnerability class: XSS (Cross-Site Scripting)
EPSS: 0.024 (81.9th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
Affected products
- Matrix Synapse
- Matrix-org Synapse — versions < 1.23.1
- Fedoraproject Fedora — versions 32, 33
Weakness classification (CWE)
Public proof-of-concept exploits
References
- security-advisories@github.com (x_refsource_CONFIRM, Third Party Advisory)
- 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 (Third Party Advisory, x_refsource_MISC, Release Notes)
- security-advisories@github.com (x_refsource_FEDORA, vendor-advisory)
- security-advisories@github.com (x_refsource_FEDORA, vendor-advisory)
Frequently asked questions
- What is CVE-2020-26257?
- CVE-2020-26257 is a medium-severity vulnerability in Matrix Synapse, classified under Cross-site Scripting. CVSS score: 6.5/10. Published 2020-12-09.
- How severe is CVE-2020-26257?
- Medium severity. CVSS v3 base score is 6.5 out of 10.
- Is CVE-2020-26257 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.