What is CVE-2026-40541?

CVE-2026-40541 is a critical-severity vulnerability in Synology Chat Server, classified under Cross-site Scripting. CVSS score: 9.0/10. Published 2026-08-28.

How severe is CVE-2026-40541?

Critical severity. CVSS v3 base score is 9.0 out of 10.

XSS in Synology Chat Server

CVE-2026-40541

An improper neutralization of input during web page generation ('Cross-site Scripting') vulnerability in extract domain in Synology Chat Server before 2.4.5-22148 allows remote authenticated users, via a UI interaction, to read or write arbitrary files and conduct denial-of-service attacks in DSM.

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.005 (39.4th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.0 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H.

Affected products

Synology Chat Server

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

security@synology.com (vendor-advisory)

Frequently asked questions

What is CVE-2026-40541?: CVE-2026-40541 is a critical-severity vulnerability in Synology Chat Server, classified under Cross-site Scripting. CVSS score: 9.0/10. Published 2026-08-28.
How severe is CVE-2026-40541?: Critical severity. CVSS v3 base score is 9.0 out of 10.