CVE-2026-40922

SiYuan: Incomplete sanitization of bazaar README allows stored XSS via iframe srcdoc (incomplete fix for CVE-2026-33066)

MEDIUM
5.4
CVSS Score
Published: April 16, 2026 at 11:14 PM UTC
Updated: June 17, 2026 at 10:45 AM UTC
2 products affected across 2 vendorsSiyuanSiyuan

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Severity
MEDIUM5.4
Exploit prediction
EPSS 0.3%
SSVC
PoC

Description

SiYuan is an open-source personal knowledge management system. In versions 3.6.1 through 3.6.3, a prior fix for XSS in bazaar README rendering (incomplete fix for CVE-2026-33066) enabled the Lute HTML sanitizer, but the sanitizer does not block iframe tags, and its URL-prefix blocklist does not effectively filter srcdoc attributes which contain raw HTML rather than URLs. A malicious bazaar package author can include an iframe with a srcdoc attribute containing embedded scripts in their README. When other users view the package in SiYuan's marketplace UI, the payload executes in the Electron context with full application privileges, enabling arbitrary code execution on the user's machine. This issue has been fixed in version 3.6.4.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

3.6.1 ≤ v < 3.6.4
v < 3.6.4
Affected range stops below 3.6.4, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (4)

x_refsource_CONFIRMExploitThird Party Advisory
Source: cverecord
https://github.com/siyuan-note/siyuan/security/advisories/GHSA-8q5w-mmxf-48jg
x_refsource_MISCThird Party Advisory
Source: cverecord
https://github.com/advisories/GHSA-4663-4mpg-879v
x_refsource_MISCRelease Notes
Source: cverecord
https://github.com/siyuan-note/siyuan/releases/tag/v3.6.4

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-79

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