CVE-2026-23847Public exploitNetwork attack vector

Session JavaScript execution via unescaped SVG content

Published Jan 19, 2026 · Updated Jan 19, 2026

Reflected XSS in SiYuan before 3.5.4 allows remote authenticated users to execute JavaScript by loading a crafted dynamic-icon SVG. At /api/icon/getDynamicIcon, type 8 places the content parameter inside an SVG text element without XML escaping, so injected tags break the document structure. The payload runs in the user's session only when the generated SVG is loaded directly, exposing session data and permitting actions available to that user.

CVSS severity5.3
Medium
EPSS probability0.31%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reflected XSS in SiYuan before 3.5.4 allows remote authenticated users to execute JavaScript by loading a crafted dynamic-icon SVG. At /api/icon/getDynamicIcon, type 8 places the content parameter inside an SVG text element without XML escaping, so injected tags break the document structure. The payload runs in the user's session only when the generated SVG is loaded directly, exposing session data and permitting actions available to that user.

The record

CVE
CVE-2026-23847
Published
Jan 19, 2026
Updated
Jan 19, 2026
Vendor
SiYuan Note
Product
SiYuan
Classifications
CWE-79, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 19, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 3.5.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

SiYuan Note · SiYuanversion=< 3.5.4

Published CVSS scores

5.3GitHubCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
6.1NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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