Vulnerability report

Active exploitation observed Confirmed confidence Not in CISA KEV

CVE-2026-86538

knowns Before 0.30.0 Path Traversal

Knowns-dev / knowns · affected before 0.30.0

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Severity
CVSS 8.7 · High
Confidence
Confirmed
Exploit status
Observed in sensors
EPSS
0.7%
First observed
14 Sep 2026
Last observed
19 Sep 2026

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2026-86538 is an unauthenticated vulnerability affecting Knowns-dev knowns. knowns versions before 0.30.0 contain a path traversal vulnerability in the POST /api/templates/preview endpoint that allows...

Is it exploited?

Yes. Previdian sensors observed exploitation attempts with confirmed confidence.

Who is affected?

Knowns-dev / knowns affected before 0.30.0.

What should we do?

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

Overview

knowns Before 0.30.0 Path Traversal

knowns versions before 0.30.0 contain a path traversal vulnerability in the POST /api/templates/preview endpoint that allows unauthenticated attackers to read arbitrary files.

Attackers can supply directory traversal sequences in the templateFile parameter to bypass path restrictions and read sensitive files like credentials and configuration through the JSON response.

knowns-dev Affected
knowns
Before 0.30.0
knowns-dev Unaffected
knowns
0.30.0
View vendor advisory (opens in new tab)
Published
07 Sep 2026
Exploitation Reported
14 Sep 2026
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

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

Previdian

Recorded 14 Sep 2026

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

Active exploitation observed

Previdian sensor

First observed 14 Sep 2026

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

Known exploited vulnerability sources

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

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Source Added
Previdian First 2026-09-17 16:27 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.

368

Attempts observed

166

Unique attacker IPs

5

Attacker countries

BE · IN · SG · TW · US

5

Sensors observed

CVE-2026-86538 exploitation attempts over the last 7 days

Daily events observed by Previdian sensors

Updated 19 Sep 2026

0
2
2
2
220
70
72
13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep

First observed 14 Sep 2026 · Last observed 19 Sep 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
User-Agents
Callback hosts
1
32
0

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

Scanner coverage

No scanner integrations recorded yet.

Virtual patch status

No Previdian 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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Risk and context

Severity, weaknesses, and research context

CVSS v4.0

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

EPSS

0.7%

Weaknesses

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') CWE-22

All CVSS Scores

CVSS v4.0 8.7 High

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

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

Timeline

From disclosure to observed exploitation

  1. 16:27 UTC

    Indicators of compromise added (166)

    Indicators of compromise recorded

  2. 16:27 UTC

    Observed by Previdian sensors

    Evidence-backed exploitation signal

  3. 23:03 UTC

    CVE published

    Vulnerability disclosed publicly

  4. 22:18 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-2026-86538

Free JSON includes basic KEV fields 
{
  "cve_id": "CVE-2026-86538",
  "confidence": "Confirmed",
  "cvss_score": 8.7,
  "cvss_estimated": false,
  "epss_score": 0.00736,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": true
  },
  "sensor_telemetry": { "attempts": 368, "sensors": 5 }
}