CVE catalog
CVE-2020-26891
UBUNTU-CVE-2020-26891
- Severity
- Medium · CVSS 6.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - Published
- Updated
- Source
- [NVD] · [CVE record]
- EPSS
- 1.92% · Oct 25, 2026
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.
Vulnerable and fixed packages
Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.
| Distribution | Package | Release | Version | Status |
|---|---|---|---|---|
| Ubuntu | matrix-synapse | pro | 0.19.2+dfsg-6 | vulnerable |
| Ubuntu | matrix-synapse | pro | 0.24.0+dfsg-1 | vulnerable |
| Ubuntu | matrix-synapse | pro | 0.24.0+dfsg-1ubuntu0.1~esm1 | vulnerable |
| Ubuntu | matrix-synapse | pro | 0.24.0+dfsg-1ubuntu0.1~esm4 | vulnerable |
| Ubuntu | matrix-synapse | pro | 1.3.0-1 | vulnerable |
| Ubuntu | matrix-synapse | pro | 1.4.0-1 | vulnerable |
| Ubuntu | matrix-synapse | pro | 1.5.0-1 | vulnerable |
| Ubuntu | matrix-synapse | pro | 1.5.1-1 | vulnerable |
| Ubuntu | matrix-synapse | pro | 1.6.0-1 | vulnerable |
| Ubuntu | matrix-synapse | pro | 1.6.1-1 | vulnerable |
| Ubuntu | matrix-synapse | pro | 1.7.0-2 | vulnerable |
| Ubuntu | matrix-synapse | pro | 1.7.1-1 | vulnerable |
| Ubuntu | matrix-synapse | pro | 1.7.2-1 | vulnerable |
| Ubuntu | matrix-synapse | pro | 1.7.3-1 | vulnerable |
| Ubuntu | matrix-synapse | pro | 1.8.0-1 | vulnerable |
| Ubuntu | matrix-synapse | pro | 1.9.0-1 | vulnerable |
| Ubuntu | matrix-synapse | pro | 1.9.1-1 | vulnerable |
| Ubuntu | matrix-synapse | pro | 1.10.0-1 | vulnerable |
| Ubuntu | matrix-synapse | pro | 1.10.0-2 | vulnerable |
| Ubuntu | matrix-synapse | pro | 1.11.0-1 | vulnerable |
| Ubuntu | matrix-synapse | pro | 1.11.0-1ubuntu0.1~esm2 | vulnerable |
| Ubuntu | matrix-synapse | pro | 1.39.0-1 | vulnerable |
| Ubuntu | matrix-synapse | pro | 1.47.0-2 | vulnerable |
| Ubuntu | matrix-synapse | pro | 1.47.1-1 | vulnerable |
| Ubuntu | matrix-synapse | pro | 1.48.0-1 | vulnerable |
| Ubuntu | matrix-synapse | pro | 1.49.0-1 | vulnerable |
| Ubuntu | matrix-synapse | pro | 1.49.2-1 | vulnerable |
| Ubuntu | matrix-synapse | pro | 1.50.1-1 | vulnerable |
| Ubuntu | matrix-synapse | pro | 1.50.2-1 | vulnerable |
| Ubuntu | matrix-synapse | pro | 1.51.0-1 | vulnerable |
| Ubuntu | matrix-synapse | pro | 1.52.0-1 | vulnerable |
| Ubuntu | matrix-synapse | pro | 1.53.0-1 | vulnerable |
| Ubuntu | matrix-synapse | pro | 1.53.0-1ubuntu0.1~esm2 | vulnerable |
Fixed-version evidence
OpenFactory catalog packages
No matching packages in this catalog.
Observed: