Is CVE-2026-54066 actively exploited?

Yes. KEVIntel has observed exploitation attempts targeting this CVE. Confidence is confirmed.

What exploitation activity has KEVIntel observed?

KEVIntel sensors have observed 2 exploitation attempts, 2 unique attacker IPs, and 2 countries targeting CVE-2026-54066. First observed Jul 19, 2026; last observed Jul 24, 2026.

Which versions are affected?

CVE-2026-54066 affects siyuan-note siyuan. Reported affected version: < 3.7.0.

How should organizations remediate it?

Prioritize immediate patching and validate internet-facing exposure. Monitor for matching exploitation attempts in your environment.

No. CVE-2026-54066 is not currently listed in CISA KEV.

Vulnerability report

Active exploitation observed Confirmed confidence Not in CISA KEV

CVE-2026-54066

Q: How should organizations remediate it?

Prioritize immediate patching and validate internet-facing exposure. Monitor for matching exploitation attempts in your environment.

Q: Is it in CISA KEV?

No. CVE-2026-54066 is not currently listed in CISA KEV.

siyuan Path Traversal

siyuan-note / siyuan · affected before 3.7.0

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Severity: CVSS 7.5 · High
Confidence: Confirmed
Exploit status: Observed in sensors
EPSS: 1.9%
First observed: 19 Jul 2026
Last observed: 24 Jul 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. KEVIntel sensors observed exploitation attempts with confirmed confidence.

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.

Vendor Product Affected Status

siyuan-note siyuan Before 3.7.0 Affected

Published: 24 Jun 2026
Exploited Since: 19 Jul 2026
Attack vector: Remote
Complexity: Low
Privileges: None
User interaction: None

CVE References

https://github.com/siyuan-note/siyuan/security/advisories/GHSA-p4m3-mgmm-c664 github.com · CVE Record https://github.com/siyuan-note/siyuan/security/advisories/GHSA-p4m3-m...

Exploitation evidence

Why KEVIntel 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

Independent exploitation attestation added to the KEVIntel record.

Active exploitation observed

KEVIntel sensor

First observed 19 Jul 2026

First-party sensor telemetry confirms matching exploitation attempts.

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 KEVIntel Pro API.

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

Operational indicators for this CVE are listed under Detection.

Sensor telemetry

First-party evidence of exploitation activity

Aggregate observations show the scale, recency, and distribution of activity without overstating sparse data.

Attempts observed

Unique attacker IPs

Attacker countries

NL · US

Sensors observed

Exploitation attempts over the last 19 days

Daily events observed by KEVIntel sensors

Updated 05 Aug 2026

First observed 19 Jul 2026 · Last observed 24 Jul 2026

Pro adds sensor region and window summaries. Enterprise adds raw IPs, paths, User-Agents, and payloads.

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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: 1
User-Agents: 2

Raw values available in Pro and Enterprise.

Scanner coverage

Nuclei template detected 25 Jun 2026.

View Nuclei template

Virtual patch status

No KEVIntel virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

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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

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

7.5 High

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

EPSS

1.9%

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

03 Aug 2026
Added to KEVIntel KEV Feed

High-confidence, third-party attested exploitation
19 Jul 2026
Observed by KEVIntel sensors

Evidence-backed exploitation signal
19 Jul 2026
Indicators of compromise added (2)

Indicators of compromise recorded
25 Jun 2026
Public PoC available

Public proof-of-concept code published
25 Jun 2026
Nuclei template available

Scanner coverage available
24 Jun 2026
CVE published

Vulnerability disclosed publicly
11 Jun 2026
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

Free JSON includes basic KEV fields

{
  "cve_id": "CVE-2026-54066",
  "confidence": "Confirmed",
  "cvss_score": 7.5,
  "epss_score": 0.01892,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": true
  },
  "sensor_telemetry": { "attempts": 2, "sensors": 2 }
}

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