VulnerabilityModified
CVE-2020-26891
AuthRestServlet in Matrix Synapse before 1.21.0 is vulnerable to XSS due to unsafe interpolation of the session GET parameter.
MEDIUM 6.1EPSS 1.93%
Does this matter?
Lower severity and a low EPSS score (1.93%). Track it; it rarely justifies an emergency change on its own.
Description
AuthRestServlet in Matrix Synapse before 1.21.0 is vulnerable to XSS due to unsafe interpolation of the session GET parameter. This allows a remote attacker to execute an XSS attack on the domain Synapse is hosted on, by supplying the victim user with a malicious URL to the /_matrix/client/r0/auth/*/fallback/web or /_matrix/client/unstable/auth/*/fallback/web Synapse endpoints.
- CVSS 3.1
- 6.1 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
- EPSS
- 1.93% probability · 79th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-79
- Affected
- matrix/synapse
- Source
- cve@mitre.org
References
- https://github.com/matrix-org/synapse/pull/8444Issue Tracking, Patch, Third Party Advisory
- https://github.com/matrix-org/synapse/releases/tag/v1.21.2Release Notes, Third Party Advisory
- https://github.com/matrix-org/synapse/security/advisories/GHSA-3x8c-fmpc-5rmqPatch, Third Party Advisory
- https://matrix.org/blog/2020/10/15/synapse-1-21-2-released-and-security-advisoryRelease Notes, Vendor Advisory
- https://github.com/matrix-org/synapse/pull/8444Issue Tracking, Patch, Third Party Advisory
- https://github.com/matrix-org/synapse/releases/tag/v1.21.2Release Notes, Third Party Advisory
- https://github.com/matrix-org/synapse/security/advisories/GHSA-3x8c-fmpc-5rmqPatch, Third Party Advisory
- https://matrix.org/blog/2020/10/15/synapse-1-21-2-released-and-security-advisoryRelease Notes, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.