Cross-Site Scripting in Synology Chat Server Domain Extraction

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.

Casky was already ahead

This CVE exploits attack patterns that Casky's 323matched skills already investigate — long before this vulnerability was disclosed. Claude's reasoning model maps these techniques to MITRE ATT&CK, so practitioners who ran these skills have already seen the threat behaviour in their findings.

Analysis

Synology Chat Server versions before 2.4.5-22148 contain a critical cross-site scripting (XSS) vulnerability in the domain extraction functionality that allows authenticated attackers to inject malicious scripts through UI interactions. With a CVSS score of 9, this vulnerability enables threat actors to read or write arbitrary files and launch denial-of-service attacks against DSM (DiskStation Manager) environments. Organizations running vulnerable Synology Chat Server instances face significant risk, particularly in environments where multiple users have authentication access to the chat platform, as the attack requires only authenticated user interaction to be exploited.

Casky's 323 mapped security skills leverage Claude AI's extended reasoning to detect attack patterns associated with TA0001 (Initial Access) and TA0043 (Reconnaissance) techniques by analyzing how XSS payloads are crafted and delivered through the domain extraction feature. Practitioners using Casky would observe findings highlighting suspicious script injection attempts in web request logs, particularly those targeting the domain extraction endpoint with encoded or obfuscated JavaScript payloads. The platform's skills would correlate user authentication events with subsequent file access or DSM manipulation activities, identifying the hallmark pattern of post-exploitation behavior where initial XSS foothold leads to lateral movement or data exfiltration within the DSM infrastructure.

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Casky Risk Score

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EPSS Probability

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Shodan Exposure

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GreyNoise Signal

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Composite risk scoring from EPSS, CISA KEV, Shodan, and GreyNoise — 21 security APIs correlated into a single Casky Risk Score. Coming in Casky Pro. Join early access →

323 Casky skills cover this attack pattern

These skills use Claude AI's reasoning model to surface findings in the same attack categories as CVE-2026-40541.

Abuse of Public-Facing API: Mobile API Abuse

mobile security · low

Run

abusing-dpapi-for-credential-access

red teaming · high

Run

abusing-shadow-credentials-for-privesc

red teaming · high

Run

MITRE ATT&CK Techniques

TA0001 TA0043

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