CVE-2026-66394
SiYuan before v3.7.3 Stored and Reflected XSS via SVG Sanitizer Bypass
Description
SiYuan before v3.7.3 contains stored and reflected cross-site scripting vulnerabilities in SVG sanitization that allows authenticated attackers to execute scripts by bypassing the HTML parser-based cleaner. Attackers can hide script tags within desc, style, or noscript elements which the HTML parser treats as raw text but browsers interpret as executable SVG content when served as image/svg+xml, enabling script execution in the application origin.
INFO
Published Date :
July 27, 2026, 4:18 p.m.
Last Modified :
July 27, 2026, 6:17 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-66394
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 4.0 | CRITICAL | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 4.0 | CRITICAL | [email protected] |
Solution
- Update SiYuan to version 3.7.3 or later.
- Avoid uploading SVG files with embedded scripts.
- Validate all SVG content before rendering.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-66394.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-66394 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-66394
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-66394 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-66394 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 27, 2026
Action Type Old Value New Value Added Reference https://github.com/siyuan-note/siyuan/security/advisories/GHSA-99rq-75j6-5j9f Added SSVC {'id': 'CVE-2026-66394', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'poc'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-07-27T17:58:40.465603Z'} -
New CVE Received by [email protected]
Jul. 27, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'siyuan-note', 'product': 'siyuan', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '3.7.3', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '3.7.3', 'versionType': 'semver'}], 'packageURL': 'pkg:golang/github.com/siyuan-note/siyuan', 'defaultStatus': 'unaffected'}] Added Description SiYuan before v3.7.3 contains stored and reflected cross-site scripting vulnerabilities in SVG sanitization that allows authenticated attackers to execute scripts by bypassing the HTML parser-based cleaner. Attackers can hide script tags within desc, style, or noscript elements which the HTML parser treats as raw text but browsers interpret as executable SVG content when served as image/svg+xml, enabling script execution in the application origin. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CVSS V3.1 AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N Added CWE CWE-79 Added Reference https://github.com/siyuan-note/siyuan/security/advisories/GHSA-99rq-75j6-5j9f Added Reference https://www.vulncheck.com/advisories/siyuan-before-stored-and-reflected-xss-via-svg-sanitizer-bypass