CVE-2026-66396: XSS (CVSS 8.4)

Description

SiYuan before v3.7.2 fails to escape the title-img Individual Attribute List value when rendering Gallery and Kanban cover images, allowing stored cross-site scripting via unescaped style attribute interpolation. Attackers with editor permissions can inject onload handlers that execute arbitrary code in the Electron renderer with full Node.js access when victims open affected documents.

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CVSS v3.1 Score

8.4

HIGH

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

EPSS — Exploit Prediction

0.0030

Probability of exploitation

0.22%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-79 Cross-site Scripting (XSS)

References

Other References

https://github.com/siyuan-note/siyuan/security/advisories/GHSA-5rxg-wh59-mg34 https://www.vulncheck.com/advisories/siyuan-before-stored-xss-to-rce-via-title-img-ial https://github.com/siyuan-note/siyuan/security/advisories/GHSA-5rxg-wh59-mg34

Frequently Asked Questions

What is CVE-2026-66396? +

SiYuan before v3.7.2 fails to escape the title-img Individual Attribute List value when rendering Gallery and Kanban cover images, allowing stored cross-site scripting via unescaped style attribute interpolation. Attackers with editor permissions can inject onload handlers that execute arbitrary code in the Electron renderer with full Node.js access when victims open affected documents. It has a CVSS v3.1 base score of 8.4 (HIGH).

How severe is CVE-2026-66396? +

CVE-2026-66396 has a CVSS v3.1 score of 8.4 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0030, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-66396? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2026-66396