SiYuan has a SVG Sanitizer Bypass via Element — Unauthenticated XSS

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

6.4 · 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 · score source

EPSS

• CVE-2026-31807: 0.46% estimated exploitation activity in the next 30 days; percentile 39.55 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

SVG Sanitizer Bypass via <animate Element — Unauthenticated XSS Summary SiYuan's SVG sanitizer (SanitizeSVG) blocks dangerous elements (<script, <iframe, <foreignobject) and removes on event handlers and javascript: in href attributes. However, it does NOT block SVG animation elements (<animate, <set) which can dynamically set attributes to dangerous values at runtime, bypassing the static sanitization. This allows an attacker to inject executable JavaScript into the unauthenticated /api/icon/getDynamicIcon endpoint (type=8), creating a reflected XSS. This is a bypass of the fix for CVE-2026-29183 (fixed in v3.5.9). Affected Component - File: kernel/util/misc.go - Function: SanitizeSVG() (lines 234-319) - Endpoint: GET /api/icon/getDynamicIcon?type=8&content=... (unauthenticated) - Version: SiYuan <= 3.5.9 Root Cause The sanitizer checks attributes on elements at parse time. SVG <animate and <set elements modify attributes at runtime — these elements are not in the sanitizer's…

Published by the source

10 Mar 2026, 23:49 UTC

Last modified by the source

10 Mar 2026, 23:49 UTC

Source last checked

26 Oct 2026, 15:15 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-5hc8-qmg8-pw27

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# Patch Next advisory brief: CVE-2026-31807

Advisory: SiYuan has a SVG Sanitizer Bypass via ` ` Element — Unauthenticated XSS
IDs: CVE-2026-31807, GHSA-5hc8-qmg8-pw27
Record: https://patchnext.com/advisories/cve-2026-31807 (revision 1, source checked 26 Oct 2026, 15:15 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/siyuan-note/siyuan/kernel 0.0.0-20260310025236-297bd526708f. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/siyuan-note/siyuan/kernel: affected < 0.0.0-20260310025236-297bd526708f; fixed in 0.0.0-20260310025236-297bd526708f

## Suggested inspection (read-only)
- Go github.com/siyuan-note/siyuan/kernel: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/siyuan-note/siyuan/kernel.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-5hc8-qmg8-pw27 (GitHub-reviewed advisory GHSA-5hc8-qmg8-pw27 lists affected ranges: Go github.com/siyuan-note/siyuan/kernel >=0 <0.0.0-20260310025236-297bd526708f)

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