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VulnerabilityPublished Updated

CVE-2026-23852: siyuan · Code Injection

Affects siyuanSource CVE Database V5

0

Public exploit available · CVSS 5.8 Medium : upgrade to 3.5.4 as a priority.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 4.0 base score
5.8Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.8% chance of exploitation in 30 days – higher than 56% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 3.5.4
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:H/E:P

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 19 Jan 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: evidence found.

    CVSS exploit maturity: proof of concept public

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CVSS vector, the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade siyuan and siyuan-note/siyuan to 3.5.4.

Affected software

ProductAffectedFixed in
siyuan-notesiyuanAffected
  • <3.5.4
Fixed in
  • 3.5.4
GitHubsiyuan-note/siyuanpkg:github/siyuan-note/siyuanOther threatsAffected
  • <3.5.4
Fixed in
  • 3.5.4

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

European organizations should immediately update all SiYuan Note installations to version 3.5.4 or later, which contains the updated fix for this vulnerability. If you cannot patch yet, restrict access to the /api/attr/setBlockAttrs API endpoint via network controls or application-layer firewalls to trusted users only. Implement strict input validation and output encoding on any custom integrations or plugins interacting with SiYuan to prevent injection of malicious attributes. Monitor logs for unusual API requests or unexpected changes to block attributes that could indicate exploitation attempts. Educate users about the risks of opening untrusted SiYuan files or links that could trigger malicious payloads. Employ endpoint protection solutions capable of detecting suspicious script execution in desktop environments. Conduct regular vulnerability scans and penetration tests focusing on web application and desktop client attack surfaces. Finally, maintain an incident response plan to quickly contain and remediate any detected exploitation.

Description

CVE-2026-23852 is a medium severity stored Cross-Site Scripting (XSS) vulnerability in SiYuan Note versions prior to 3.5.4. It allows attackers to inject arbitrary HTML attributes into the 'icon' attribute of a block via the /api/attr/setBlockAttrs API. The injected payload is rendered unsanitized in the dynamic icon feature, leading to stored XSS and, in the desktop environment, potential remote code execution (RCE). This vulnerability bypasses a previous fix and affects personal knowledge management systems using vulnerable SiYuan versions. No known exploits are currently reported in the wild. The vulnerability has a CVSS 4.0 score of 5.8, indicating medium severity.

References

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