CVE-2020-26891 — Cross-site Scripting in Synapse

CWE-79 — Cross-site Scripting6 documents5 sources
Severity
6.1MEDIUMNVD
EPSS
0.6%
top 30.05%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
1
Matrix Synapse
Timeline
PublishedOct 19

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 vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:NExploitability: 2.8 | Impact: 2.7

Affected Packages1 packages

▶NVDmatrix/synapse< 1.21.0

Patches

Patch: github.com ↗Patch: github.com ↗Patch: github.com ↗

🔴Vulnerability Details

4
OSV
CVE-2020-26891: AuthRestServlet in Matrix Synapse before 1↗2020-10-19
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CVEList
CVE-2020-26891: AuthRestServlet in Matrix Synapse before 1↗2020-10-19
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GHSA
Cross-site scripting (XSS) vulnerability in the fallback authentication endpoint↗2020-10-16
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OSV
Cross-site scripting (XSS) vulnerability in the fallback authentication endpoint↗2020-10-16
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📋Vendor Advisories

1
Debian
CVE-2020-26891: matrix-synapse - AuthRestServlet in Matrix Synapse before 1.21.0 is vulnerable to XSS due to unsa...↗2020
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CVE-2020-26891 — Cross-site Scripting in Matrix Synapse | cvebase