Vulnerability report

Active exploitation observed Confirmed confidence Not in CISA KEV

CVE-2026-54066

siyuan Path Traversal

Siyuan-note / siyuan · affected before 3.7.0

Watch CVE-2026-54066 Browse KEV feed
Severity
CVSS 7.5 · High
Confidence
Confirmed
Exploit status
Observed in sensors
EPSS
2.4%
First observed
19 Jul 2026
Last observed
11 Oct 2026

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2026-54066 is an unauthenticated vulnerability affecting Siyuan-note siyuan. SiYuan is an open-source personal knowledge management system. Prior to 3.7.0, the patch for CVE-2026-41894 ("Path Traversal via Double...

Is it exploited?

Yes. Previdian sensors observed exploitation attempts with confirmed confidence. Also confirmed by third-party sources.

Who is affected?

Siyuan-note / siyuan affected before 3.7.0.

What should we do?

Patch immediately, validate internet-facing exposure, and monitor for matching requests.

Overview

SiYuan is an open-source personal knowledge management system

SiYuan is an open-source personal knowledge management system. Prior to 3.7.0, the patch for CVE-2026-41894 ("Path Traversal via Double URL Encoding") sanitized the /export/ route but the identical root cause remains in the /assets/*path route. In publish mode (anonymous read-only HTTP endpoint, default port 6808), an unauthenticated remote attacker can read arbitrary files inside WorkspaceDir — including conf/conf.json (which contains the AccessAuthCode SHA256 hash, API token, and sync keys), temp/siyuan.db, temp/blocktree.db, and siyuan.log — by double-URL-encoding ..

segments. This vulnerability is fixed in 3.7.0.

siyuan-note Affected
siyuan
Before 3.7.0
Published
24 Jun 2026
Exploited Since
19 Jul 2026
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

Tags

nuclei_scanner

CVE References

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

The Shadowserver

Recorded 03 Aug 2026

Previdian independently recorded this as exploited after first seeing it in honeypot sensors.

Active exploitation observed

Previdian sensor

First observed 19 Jul 2026

Previdian first observed exploitation attempts targeting this vulnerability in our honeypot sensors.

Proof of concept available

Nuclei Templates

Recorded 25 Jun 2026

Public scanner or PoC coverage increases practical exploitability.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

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Source Added
The Shadowserver First 2026-08-03 00:00 UTC
Previdian Sensors 2026-08-04 13:47 UTC

Operational indicators for this CVE are listed under Detection.

Sensor telemetry

First-party evidence of exploitation activity

Previdian sensors recorded exploitation attempts targeting this vulnerability. The cards and chart show volume, unique attackers, and daily activity.

8

Attempts observed

8

Unique attacker IPs

7

Attacker countries

CH · HK · ID · NL · SC · US · YE

8

Sensors observed

CVE-2026-54066 exploitation attempts over the last 91 days

Daily events observed by Previdian sensors

Updated 17 Oct 2026

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19 Jul 7 Aug 26 Aug 14 Sep 17 Oct

First observed 19 Jul 2026 · Last observed 11 Oct 2026

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Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts
1
4
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Virtual patch status

Previdian virtual patch guidance is available for this CVE.

AWS WAF Cloudflare ModSecurity

Attacker IP Indicators

Attacker IP indicators observed · available in Pro and Enterprise.

Sensor-derived attacker IP indicators are available to Pro and Enterprise accounts under Detection and through the Pro API.

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Scanner Artifacts

Scanner and exploit-framework references linked to this CVE.

Scanner Reference Detected
Nuclei https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-54066.yaml 25 Jun 2026

Virtual Patch Detail

Compensating WAF rules for this CVE.

Available

Enterprise feature. Virtual patch rule content and deployable vendor exports (ModSecurity, Cloudflare, AWS WAF) are available to Previdian Enterprise users.

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Risk and context

Severity, weaknesses, and research context

CVSS v3.1

7.5 High

Potential damage if exploited. Separate from whether attackers are using it.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS

2.4%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

Initialization of a Resource with an Insecure Default CWE-1188 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') CWE-22 Relative Path Traversal CWE-23

Recent mention · Github Advisory Database (Go)

[github.com/siyuan-note/siyuan/kernel] SiYuan: Path Traversal via Double URL Encoding in /assets/*path (publish mode arbitrary file─read), Incomplete fix of CVE-2026-41894

Summary The patch for CVE-2026-41894 ("Path Traversal via Double URL Encoding") sanitized the /export/ route but the identical root cause remains in the /assets/*path route. In publish mode (anonymous read-only HTTP endpoint, default port 6808), an unauthenticated remote...

Read full advisory

Potential Proof of Concepts

These PoCs are unverified and could contain malware. Use at your own risk.

SiYuan <= 3.6.5 - Unauthenticated Path Traversal

nuclei · Created Unknown

Timeline

From disclosure to observed exploitation

  1. 11:35 UTC

    Virtual patch available

    Compensating WAF rule available to block exploitation

  2. 00:00 UTC

    Added to Previdian KEV Feed

    High-confidence, third-party attested exploitation

  3. 02:12 UTC

    Indicators of compromise added (8)

    Indicators of compromise recorded

  4. 02:12 UTC

    Observed by Previdian sensors

    Evidence-backed exploitation signal

  5. 04:30 UTC

    Public PoC available

    Public proof-of-concept code published

  6. 04:30 UTC

    Nuclei template available

    Scanner coverage available

  7. 21:13 UTC

    CVE published

    Vulnerability disclosed publicly

  8. 18:24 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2026-54066

Sample API response 
{
  "cve_id": "CVE-2026-54066",
  "confidence": "Confirmed",
  "cvss_score": 7.5,
  "cvss_estimated": false,
  "epss_score": 0.02386,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": true
  },
  "sensor_telemetry": { "attempts": 8, "sensors": 8 }
}