8.8High
CVE-2026-93923
SiYuan through 3.8.4 fails to escape heading style attributes when rendering outline and bookmark dock HTML, allowing stored cross-site scripting. Attackers can supply crafted notebooks or call administrative endpoints to inject malicious style values that execute in the Electron renderer with full system access.
What this means for your business
- An attacker can use it remotely, over a network, without a login, but only after tricking someone into an action such as opening a file or a link.
What to do
- 1Ask your IT team or provider whether any of your systems use the affected product.
- 2If you do, follow the vendor's guidance. No patch reference has been published yet.
Not sure if your company is exposed?
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Scoring
- CVSS
- 8.8 (v3.1)
- Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H- CVSS v4
- 8.6
- Weakness
- CWE-79
- Assigned by
- disclosure@vulncheck.com
Dates
- Published
- 2026-09-19
- Last modified
- 2026-09-21
- Sources
- NVD
References
- https://github.com/siyuan-note/siyuan
- https://github.com/siyuan-note/siyuan/blob/v3.8.4/app/src/util/Tree.ts#L133
- https://github.com/siyuan-note/siyuan/blob/v3.8.4/app/src/util/Tree.ts#L194
- https://github.com/siyuan-note/siyuan/blob/v3.8.4/kernel/model/render.go#L71-L76
- https://github.com/siyuan-note/siyuan/security/advisories/GHSA-928g-4hfq-qwvx
- https://www.vulncheck.com/advisories/siyuan-through-3.8.4-stored-xss-via-heading-style-attribute