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CVE-2026-92986· NVD / CVE Program· CNA VulnCheck

SiYuan before 3.8.4 Cross-Site Scripting via Document Title

SiYuan before 3.8.4 renders document titles as HTML in the backlink dock tree without escaping markup characters. Attackers can set malicious titles through the rename API or crafted notebooks to execute scripts in the Electron renderer with access to child_process for command execution.

HighCVSS 8.6 · v4.0—No exploit Fix available

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Published
Sep 17, 2026
Updated
Sep 17, 2026
EPSS
0.8% · 55th percentile
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Report tools

JSON

Action score

34

Monitor

Low priority for now.

CVSS
34 / 40 · 8.6 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.8%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · VulnCheck
8.6
NVD has not scored this yet; the score shown is the CNA’s.

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Affected systems

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (VulnCheck). Independent of NVD's CPE analysis and usually ahead of it.

  • siyuan-note siyuan

    • before 3.8.4affected · semver

Same product

siyuan-note: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-66012SiYuan before v3.7.2 Unauthenticated Administrator Takeover via MCP
    40Plan
  • CVE-2026-72811SiYuan before v3.7.4 SQL Injection via backlink search
    39Monitor
  • CVE-2026-69085SiYuan before v3.7.3 SQL Injection via searchDocs
    39Monitor
  • CVE-2026-69084SiYuan before v3.7.3 SQL Injection via searchEmbedBlock
    39Monitor
  • CVE-2026-69083SiYuan before v3.7.3 SQL Injection via fullTextSearchAssetContent
    39Monitor
  • CVE-2026-54158SiYuan: Stored XSS to RCE via attribute-view cell rendering in genAVValueHTML()
    39Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
siyuan-note siyuan3.8.4Vendor (CNA)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-5055185 days apartSiYuan: Stored XSS to RCE via Unsanitized Attribute View Asset Cell Content
    39Monitor
  • CVE-2026-5406785 days apartSiYuan: Stored XSS to RCE via CSS-snippet <style> breakout in renderSnippet()
    39Monitor
  • CVE-2026-5415885 days apartSiYuan: Stored XSS to RCE via attribute-view cell rendering in genAVValueHTML()
    39Monitor
  • CVE-2026-8265318 days apartSiYuan before v3.8.1 Stored XSS via confirmDialog
    37Monitor
  • CVE-2026-8265418 days apartSiYuan before v3.8.1 Stored XSS via block name
    37Monitor
  • CVE-2026-7591629 days apartSiYuan XSS-to-RCE via unescaped block metadata in hint popup
    37Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
A
Scope
X

Weakness class (CWE)

CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

nvd-secondary

Root cause

User content is inserted into the page as HTML. The browser interprets the content as code rather than data.

The bug in code

The whole CWE-79 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

ts
commentEl.innerHTML = comment.body;

Fixed

ts
commentEl.textContent = comment.body;

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records