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Fencer Vulns
high 8.6

CVE-2026-34585 json

SiYuan: Stored XSS in imported .sy.zip content leads to arbitrary command execution

published 2026-03-31 7 mo ago modified 2026-06-25 4 mo ago also EUVD-2026-17685 , GHSA-ff66-236v-p4fg , GO-2026-5357

cvss
8.6
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 28%
public exploits
0
none known

Summary

SiYuan is a personal knowledge management system. Prior to version 3.6.2, a vulnerability allows crafted block attribute values to bypass server-side attribute escaping when an HTML entity is mixed with raw special characters. An attacker can embed a malicious IAL value inside a .sy document, package it as a .sy.zip, and have the victim import it through the normal Import -> SiYuan .sy.zip workflow. Once the note is opened, the malicious attribute breaks out of its original HTML context and injects an event handler, resulting in stored XSS. In the Electron desktop client, this XSS reaches remote code execution because injected JavaScript runs with access to Node/Electron APIs. This issue has been patched in version 3.6.2.

Patch / fix

  • go github.com/siyuan-note/siyuan/kernel 0.0.0-20260329142331-918d1bd9f967
  • b3log siyuan 3.6.2
  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1

opensuse advisories openSUSE-SU-2026:21483-1

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
7 mo ago

Exploit prediction

0.35% chance of exploitation in the next 30 days, higher than 28% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/siyuan-note/siyuan/security/advisories/GHSA-ff66-236v-p4fg referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 8.6 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
GitHub 3.1 8.6 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
NVD 3.1 8.2 CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
go github.com/siyuan-note/siyuan/kernel
<0.0.0-20260329142331-918d1bd9f967
0.0.0-20260329142331-918d1bd9f967

Affected products

  • siyuan-note siyuan

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation
  • CWE-94 Improper Control of Generation of Code

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.