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VulnerabilityPublished

CVE-2026-23847: siyuan · Cross-site Scripting

Affects siyuanSource CVE Database V5

0

Public exploit available · CVSS 2.1 Low : upgrade to 3.5.4 as a priority.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 4.0 base score
2.1Low
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 24% 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:L/SI:L/SA:N/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 upgrade all SiYuan deployments to version 3.5.4 or later, where the vulnerability is patched. If upgrading is not immediately feasible, implement strict input validation and sanitization on the 'content' parameter at the web application firewall (WAF) or reverse proxy level to block malicious payloads attempting to inject SVG or script tags. Employ Content Security Policy (CSP) headers to restrict the execution of inline scripts and limit the sources of executable code, mitigating the impact of any successful XSS attempts. Monitor web server logs for suspicious requests to /api/icon/getDynamicIcon with unusual or encoded payloads. Educate users about the risks of clicking untrusted links, especially those that may contain SVG content. Conduct regular security assessments and penetration testing focusing on client-side vulnerabilities. Finally, isolate SiYuan instances from public internet exposure where possible, restricting access to trusted internal networks.

Description

CVE-2026-23847 is a reflected cross-site scripting (XSS) vulnerability in SiYuan, a personal knowledge management system, affecting versions prior to 3.5.4. The flaw exists in the /api/icon/getDynamicIcon endpoint, which generates SVG images for text icons by inserting user-supplied content directly into an SVG <text> tag without proper XML escaping. Because the response is served with the image/svg+xml content type, attackers can inject malicious JavaScript by breaking the XML structure, leading to script execution in the victim's browser. The vulnerability requires no authentication but does require user interaction to trigger the malicious payload. The CVSS 4.0 score is low (2.1), reflecting limited impact and ease of exploitation. The issue was patched in version 3.

References

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