CVE-2026-32940 SiYuan has a SanitizeSVG bypass via data:text/xml in getDynamicIcon (incomplete fix for CVE-2026-29183)
An attacker can execute arbitrary JavaScript in a victim's browser via a crafted URL due to an incomplete SVG sanitization bypass in SiYuan.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-32940?
CVE-2026-32940 is a critical cross-site scripting vulnerability in B3log Siyuan, published on 20 Mar 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
SiYuan is a personal knowledge management system. In versions 3.6.0 and below, SanitizeSVG has an incomplete blocklist — it blocks data:text/html and data:image/svg+xml in href attributes but misses data:text/xml and data:application/xml, both of which can render SVG with JavaScript execution. The unauthenticated /api/icon/getDynamicIcon endpoint serves user-controlled input (via the content parameter) directly into SVG markup using fmt.Sprintf with no escaping, served as Content-Type: image/svg+xml. This creates a click-through XSS: a victim navigates to a crafted URL, sees an SVG with an injected link, and clicking it triggers JavaScript via the bypassed MIME types. The attack requires direct navigation to the endpoint or <object>/<embed> embedding, since <img> tag rendering in the frontend doesn't allow interactive links. This issue has been fixed in version 3.6.1.
Which versions are affected by CVE-2026-32940?
3 open source packages ship an affected version, including github.com/siyuan-note/siyuan. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/siyuan-note/siyuan Go | All versions | None |
github.com/siyuan-note/siyuan Go | All versions to 0.0.0-20260313024916-fd6526133bb3 | None |
github.com/siyuan-note/siyuan Go | All versions to 0.0.0-20260313024916-fd6526133bb3 | None |
Products include B3log Siyuan.
How do I fix CVE-2026-32940?
Upgrade to a fixed version.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-32940 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-32940 exists.
Other vulnerabilities in B3log Siyuan
- CVE-2026-32938 SiYuan has an Arbitrary File Read in its Desktop Publish Service
- CVE-2026-33669 SiYuan has Arbitrary Document Reading within the Publishing Service
- CVE-2026-33670 SiYuan has directory traversal within its publishing service
- CVE-2026-32767 SiYuan: Authorization Bypass Allows Arbitrary SQL Execution via Search API
- CVE-2024-53504 SQL injection in n/a
Sources
Also known as GHSA-4mx9-3c2h-hwhg, GO-2026-4721.