CVE-2026-86712Public exploitNetwork attack vector

Code execution via forged clipboard format

Published Sep 8, 2026 · Updated Sep 10, 2026

Cross-site scripting in SiYuan before 3.8.2 allows remote attackers to execute code when a user pastes content from a crafted web page. The paste handler treats forged text/siyuan data or specially marked plain text as trusted, bypasses Lute.Sanitize, and writes the payload into executable DOM sinks. Copying attacker-controlled content and pasting it into a desktop note is required; injected script then gains Node.js access at the user's privileges.

CVSS severity8.9
High
EPSS probability0.38%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in SiYuan before 3.8.2 allows remote attackers to execute code when a user pastes content from a crafted web page. The paste handler treats forged text/siyuan data or specially marked plain text as trusted, bypasses Lute.Sanitize, and writes the payload into executable DOM sinks. Copying attacker-controlled content and pasting it into a desktop note is required; injected script then gains Node.js access at the user's privileges.

The record

CVE
CVE-2026-86712
Published
Sep 8, 2026
Updated
Sep 10, 2026
Vendor
SiYuan Note
Product
SiYuan
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 8, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 10, 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=0 <3.8.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

SiYuan Note · SiYuanversion=0 <3.8.2

Published CVSS scores

8.6VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
8.9GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

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
Privilegesunauthenticated
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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