CVE-2026-82654: SiYuan before v3.8.1 Stored XSS via block name

Severity: high (CVSS 8.9 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-30 · updated 2026-09-01
Weakness: CWE-79

Description

SiYuan before v3.8.1 fails to properly escape block name, alias, and memo fields in hint, backlink, and breadcrumb rendering functions. Attackers can set a block's name to contain HTML/script tags that execute when another user views documents referencing or displaying that block.

Affected products

siyuan-note siyuan: before 3.8.1 — fixed in 3.8.1

How to fix

Upgrade to a fixed version: siyuan-note siyuan 3.8.1. Check the vendor advisory for mitigations.

References

https://github.com/siyuan-note/siyuan/security/advisories/GHSA-hf87-qh3j-3p88
https://www.vulncheck.com/advisories/siyuan-before-3.8.1-stored-xss-via-block-name

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