Stored XSS in SiYuan Package Management Dialog

SiYuan before v3.8.1 contains a stored cross-site scripting vulnerability in confirmDialog() where unescaped package names and notebook names are interpolated directly into innerHTML assignments. Attackers can submit malicious bazaar packages with HTML/script payloads in the name field that execute in users' browsers when uninstalling packages or unlocking encrypted notebooks.

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

SiYuan before v3.8.1 contains a stored cross-site scripting vulnerability in its confirmDialog() function where package and notebook names are directly interpolated into innerHTML without proper sanitization. When users uninstall bazaar packages or unlock encrypted notebooks, malicious HTML and JavaScript payloads embedded in package names execute in their browsers with full user context. This affects any SiYuan user interacting with third-party packages from the bazaar marketplace, creating a supply-chain attack vector where threat actors can distribute weaponized packages designed to steal credentials, exfiltrate notes, or compromise the user's system. With a CVSS score of 8.9, this represents a significant risk for knowledge workers and organizations relying on SiYuan for sensitive note-taking and documentation.

Casky.ai's 323 mapped skills leverage Claude's extended reasoning to detect the attack patterns behind this vulnerability across two MITRE ATT&CK techniques: Initial Access (TA0001) through malicious bazaar package distribution, and Execution (TA0043) when the XSS payload triggers in the user's browser context. A practitioner using Casky would observe findings highlighting unsafe DOM manipulation patterns, detection of script injection in UI dialog components, and behavioral analysis showing how user interactions with package management features can be weaponized. The platform's skills would specifically flag the CWE-79 (Improper Neutralization of Input During Web Page Generation) root cause, tracking how unvalidated package metadata flows directly to innerHTML assignments, enabling attackers to achieve arbitrary code execution within the SiYuan application's privilege level.

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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-2026-82653.

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

Investigate the attack patterns behind CVE-2026-82653

Casky has 323 skills that investigate the attack patterns behind CVE-2026-82653. Run one and get CVSS-scored findings in 3 minutes.

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