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CVE-2026-40922

MEDIUMCVSS 5.3/10EPSS 0.26%

Last modified

CVE-2026-40922 is a medium-severity vulnerability rated 5.3/10 on the CVSS scale. 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. EPSS estimates a 0.26% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
5.4/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

CVSS 4.0
5.3/10

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/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

EPSS Probability
0.26%

17.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
B3logSiyuan>= 3.6.1, < 3.6.4

References

Timeline

Published
Last Modified
Status
Modified

Frequently Asked Questions

What is CVE-2026-40922?
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.
How severe is CVE-2026-40922?
CVE-2026-40922 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 0.26% probability of exploitation in the next 30 days.
How do I fix CVE-2026-40922?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-40922?

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Source: NVD / NIST