CVE-2020-26891 — Vulnetix

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CVE-2020-26891 PUBLISHED

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.

EPSS 0.62% · 69.7th percentile

Risk Scores

EPSS Score

0.62%

69.7th percentile

Affected Products

Vendor	Product	Versions
Ubuntu:Pro:18.04:LTS	matrix-synapse	0, 0.19.2+dfsg-6, 0.24.0+dfsg-1
Ubuntu:Pro:20.04:LTS	matrix-synapse	0, 1.4.0-1, 1.5.0-1
Ubuntu:Pro:22.04:LTS	matrix-synapse	1.39.0-1, 1.47.0-2, 1.47.1-1

Timeline

Oct 16, 2020 CVE Published
Apr 14, 2021 EPSS Score
Jun 22, 2021 EPSS Score
Aug 23, 2021 EPSS Score
Dec 25, 2021 EPSS Score
Jan 6, 2022 EPSS Score
Feb 4, 2022 EPSS Score
Feb 25, 2022 EPSS Score
Apr 1, 2022 EPSS Score
Jun 29, 2022 EPSS Score
Aug 31, 2022 EPSS Score
Nov 1, 2022 EPSS Score

References

https://ubuntu.com/security/CVE-2020-26891 third-party-advisory
https://github.com/matrix-org/synapse/pull/8444 third-party-advisory
https://github.com/matrix-org/synapse/releases third-party-advisory
https://matrix.org/blog/2020/10/15/synapse-1-21-2-released-and-security-advisory third-party-advisory
https://www.cve.org/CVERecord?id=CVE-2020-26891 third-party-advisory

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