Vulnerability · Published Mar 10, 2026 · Assigned by GitHub_M

CVE-2026-31809SiYuan has a SVG Sanitizer Bypass via Whitespace in `javascript:` URI — Unauthenticated XSS

Medium 6.4

In plain English

A medium-severity cross-site scripting in siyuan from siyuan-note. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 47% of all known vulnerabilities). Ready-made attack tooling exists: Nuclei. Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)6.4Medium

Exploit odds (30 days)0.6%top 53.1% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack tooling1Nuclei

Official description

SiYuan is a personal knowledge management system. Prior to 3.5.10, SiYuan's SVG sanitizer (SanitizeSVG) checks href attributes for the javascript: prefix using strings.HasPrefix(). However, inserting ASCII tab (	), newline (
), or carriage return () characters inside the javascript: string bypasses this prefix check. Browsers strip these characters per the WHATWG URL specification before parsing the URL scheme, so the JavaScript still executes. This allows an attacker to inject executable JavaScript into the unauthenticated /api/icon/getDynamicIcon endpoint, creating a reflected XSS. This is a second bypass of the fix for CVE-2026-29183 (fixed in v3.5.9). This vulnerability is fixed in 3.5.10.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Go	github.com/siyuan-note/siyuan/kernel	0.0.0-20260310025236-297bd526708f	GHSA-pmc9-f5qr-2pcr
Go	github.com/siyuan-note/siyuan/kernel	0.0.0-20260310025236-297bd526708f	GO-2026-4669

Affected products (as reported)

Vendor	Product	Versions
siyuan-note	siyuan	< 3.5.10

Weakness: CWE-79 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N

References

https://github.com/siyuan-note/siyuan/security/advisories/GHSA-pmc9-f5qr-2pcr x_refsource_CONFIRM