CVE-2026-29183 is a critical-severity (CVSS 9.3) Cross-site Scripting (XSS) vulnerability in github.com/siyuan-note/siyuan/kernel. A fix is available for github.com/siyuan-note/siyuan/kernel — see the affected versions and patch details below.
SiYuan: Unauthenticated reflected SVG XSS in `/api/icon/getDynamicIcon` (`type=8`) enables arbitrary JavaScript execution
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-29183.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-29183 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
github.com/siyuan-note/siyuan/kernelReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Summary
An unauthenticated reflected XSS vulnerability exists in the dynamic icon API endpoint:
GET /api/icon/getDynamicIcon
When type=8, attacker-controlled content is embedded into SVG output without escaping. Because the endpoint is unauthenticated and returns image/svg+xml, a crafted URL can inject executable SVG/HTML event handlers (for example onerror) and run JavaScript in the SiYuan web origin.
This can be chained to perform authenticated API actions and exfiltrate sensitive data when a logged-in user opens the malicious link.
Details
The issue is caused by unsafe output construction and incomplete sanitization:
-
Endpoint is exposed without auth middleware
- Source: https://github.com/siyuan-note/siyuan/blob/master/kernel/api/router.go#L27-L37
GET /api/icon/getDynamicIconis registered in the unauthenticated section.
-
User input is inserted into SVG via string formatting
- Source: https://github.com/siyuan-note/siyuan/blob/master/kernel/api/icon.go#L115-L175
- Source: https://github.com/siyuan-note/siyuan/blob/master/kernel/api/icon.go#L537-L585
- In
generateTypeEightSVG,%sdirectly injectscontentinto<text>...</text>without XML/HTML escaping.
-
Sanitizer only removes
<script>tags- Source: https://github.com/siyuan-note/siyuan/blob/master/kernel/util/misc.go#L235-L281
RemoveScriptsInSVGremoves<script>nodes, but does not remove dangerous attributes (onerror,onload, etc.) or unsafe elements.
As a result, payloads such as </text><image ... onerror=...><text> survive and execute.
PoC
Minimal browser execution PoC
Open this URL in a browser:
GET /api/icon/getDynamicIcon?type=8&content=%3C%2Ftext%3E%3Cimage%20href%3Dx%20onerror%3Dalert(document.domain)%3E%3C%2Fimage%3E%3Ctext%3E
Example full URL:
http://127.0.0.1:6806/api/icon/getDynamicIcon?type=8&content=%3C%2Ftext%3E%3Cimage%20href%3Dx%20onerror%3Dalert(document.domain)%3E%3C%2Fimage%3E%3Ctext%3E
Expected result:
- JavaScript executes (
alert(document.domain)), confirming reflected XSS.
Authenticated impact demonstration
If a victim is authenticated in the same browser session, JavaScript running in origin can call privileged APIs and exfiltrate returned data.
Impact
This is a reflected XSS in an unauthenticated endpoint, with realistic account/data compromise impact:
- Arbitrary JavaScript execution in SiYuan web origin.
- Authenticated action abuse via same-origin API calls.
- Sensitive data exposure (notes/config/API responses) from victim context.
- Potential chained server-impact actions depending on victim privileges and deployment mode.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/siyuan-note/siyuan/kernel | all versions | 0.0.0-20260304034809-d68bd5a79391go get github.com/siyuan-note/siyuan/kernel@v0.0.0-20260304034809-d68bd5a79391 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/siyuan-note/siyuan/kernel, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/siyuan-note/siyuan/kernel to 0.0.0-20260304034809-d68bd5a79391 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-29183 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-29183 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-29183. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
How to detect CVE-2026-29183
A community-maintained Nuclei template exists for this CVE. You can scan for it directly:
nuclei -id cve-2026-29183 -u https://target- Template
- SiYuan Note - Cross-Site Scripting
- Severity
- medium
- Impact
- Successful exploitation allows arbitrary JavaScript execution in the SiYuan web origin. Attackers can abuse authenticated API actions and exfiltrate sensitive data if a privileged session is active.
- Remediation
- Upgrade to SiYuan version 3.5.9 or later, which properly sanitizes SVG content.
Template by ProjectDiscovery nuclei-templates (ritikchaddha), MIT licensed. View the full template. Scan only systems you are authorised to test.
Frequently Asked Questions
Is CVE-2026-29183 in your dependencies?
O3 Security finds CVE-2026-29183 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.