Detections
Analytics

SCA: security update for matrix-synapse (GHSA-3x8c-fmpc-5rmq)

medium Tenable Cloud Security Plugin ID 409761

Description

There are packages installed that are affected by a vulnerability referenced in the following CVE:

 - 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. (CVE-2020-26891)

See Also

https://github.com/advisories/GHSA-3x8c-fmpc-5rmq

Plugin Details

Severity: Medium

ID: 409761

Version: Revision 1.4

Type: Local

Family: SCA Checks

Published: 1/23/2025

Updated: 7/2/2026

Supported Sensors: Tenable Cloud Security, Tenable Self-Hosted Container Security

Risk Information

VPR

Risk Factor: Low

Score: 2.3

Percentile: 8.67

Vendor

Vendor Severity: Medium

CVSS v2

Risk Factor: Medium

Base Score: 4.3

Temporal Score: 3.2

Vector: CVSS2#AV:N/AC:M/Au:N/C:N/I:P/A:N

CVSS Score Source: CVE-2020-26891

CVSS v3

Risk Factor: Medium

Base Score: 6.1

Temporal Score: 5.3

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

CVSS v4

Risk Factor: Medium

Base Score: 5.1

Threat Score: 1.2

Threat Vector: CVSS:4.0/E:U

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

Vulnerability Information

Exploit Ease: No known exploits are available

Patch Publication Date: 10/16/2020

Vulnerability Publication Date: 10/16/2020

Reference Information

CVE: CVE-2020-26891

cwe: CWE-79