CVE-2026-40541Network attack vector

Arbitrary file access via extract domain XSS

Published Aug 28, 2026 · Updated Aug 28, 2026

Cross-site scripting in extract domain in Synology Chat Server before 2.4.5-22148 allows remote authenticated users to read or write files. Synology has not disclosed how extract domain fails to neutralize attacker-controlled input during web page generation. Exploitation requires authentication and UI interaction and can also interrupt DSM service.

CVSS severity9.0
Critical
EPSS probability0.48%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in extract domain in Synology Chat Server before 2.4.5-22148 allows remote authenticated users to read or write files. Synology has not disclosed how extract domain fails to neutralize attacker-controlled input during web page generation. Exploitation requires authentication and UI interaction and can also interrupt DSM service.

The record

CVE
CVE-2026-40541
Published
Aug 28, 2026
Updated
Aug 28, 2026
Vendor
Synology
Product
Synology Chat Server
Classifications
CWE-79
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 28, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 28, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=* <2.4.5-22148

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Synology · Synology Chat Serverversion=* <2.4.5-22148

Published CVSS scores

9.0SynologyCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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