CVE-2026-23645Public exploitNetwork attack vector

Stored XSS via unsanitized uploaded SVG scripts

Published Jan 16, 2026 · Updated Jan 16, 2026

Stored XSS in SiYuan before 3.5.4-dev2 allows remote authenticated users to execute JavaScript by opening a crafted uploaded SVG. The asset-serving path returns uploaded SVG files as image/svg+xml without removing embedded script elements, so a browser executes them in the application origin. Exploitation requires an authenticated user to import or upload the SVG and then export or directly open it; script execution can read or alter data available to that session.

CVSS severity5.1
Medium
EPSS probability0.28%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in SiYuan before 3.5.4-dev2 allows remote authenticated users to execute JavaScript by opening a crafted uploaded SVG. The asset-serving path returns uploaded SVG files as image/svg+xml without removing embedded script elements, so a browser executes them in the application origin. Exploitation requires an authenticated user to import or upload the SVG and then export or directly open it; script execution can read or alter data available to that session.

The record

CVE
CVE-2026-23645
Published
Jan 16, 2026
Updated
Jan 16, 2026
Vendor
SiYuan Note
Product
SiYuan
Classifications
CWE-79, T1204.002
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 16, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 16, 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-dev2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

SiYuan Note · SiYuanversion=< 3.5.4-dev2

Published CVSS scores

5.1GitHubCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 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')
T1204.002User Execution: Malicious File

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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