Vulnerability report

Active exploitation observed Confirmed confidence Not in CISA KEV

CVE-2026-106173

FortiSIEM Path traversal

Fortinet / FortiSIEM · 7.5.0

Watch CVE-2026-106173 Browse KEV feed
Severity
CVSS 9.8 · Critical
Confidence
Confirmed
Exploit status
Observed in sensors
EPSS
0.5%
First observed
23 Oct 2026
Last observed
23 Oct 2026

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2026-106173 is an unauthenticated vulnerability affecting Fortinet FortiSIEM. A improper limitation of a pathname to a restricted directory ('path traversal') vulnerability in Fortinet FortiSIEM 7.5.0 may allow...

Is it exploited?

Yes. Previdian sensors observed exploitation attempts with confirmed confidence.

Who is affected?

Fortinet / FortiSIEM 7.5.0.

What should we do?

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

Overview

FortiSIEM Path traversal

A improper limitation of a pathname to a restricted directory ('path traversal') vulnerability in Fortinet FortiSIEM 7.5.0 may allow attacker to execute unauthorized code or commands via specially crafted packets.

Fortinet Affected
FortiSIEM
7.5.0 Through 7.4.2 Through 7.3.5 Through 7.2.7 Through 7.1.9 Through 7.0.4
Published
13 Oct 2026
Exploitation Reported
23 Oct 2026
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

Tags

edge

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 23 Oct 2026

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

Active exploitation observed

Previdian sensor

First observed 23 Oct 2026

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

Proof of concept available

GitHub

Recorded 20 Oct 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.

Learn about Pro API access
Source Added
Previdian Sensors First 2026-10-23 09:56 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.

2

Attempts observed

2

Unique attacker IPs

2

Attacker countries

EE · NL

2

Sensors observed

CVE-2026-106173 exploitation attempts over the last 7 days

Daily events observed by Previdian sensors

Updated 24 Oct 2026

0
0
0
0
0
2
0
18 Oct 19 Oct 20 Oct 21 Oct 22 Oct 23 Oct 24 Oct

First observed 23 Oct 2026 · Last observed 23 Oct 2026

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

Start 14-day Pro trial

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
0
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.

Learn about virtual patches →

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.

Learn about Pro API access

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

9.8 Critical

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:H/A:H

EPSS

0.5%

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

Weaknesses

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

Recent mention · The Hacker News

Critical FortiSIEM Flaw Gets Public Exploit PoC for Unauthenticated Remote Code Execution

Cybersecurity researchers have released a proof-of-concept (PoC) exploit for a recently patched critical security flaw impacting Fortinet FortiSIEM that could result in arbitrary code execution. The vulnerability, tracked as CVE-2026-106173 (CVSS score: 9.4), is a critical...

Read full advisory

All Mentions

Recent mention · The Hacker News

Critical FortiSIEM Flaw Gets Public Exploit PoC for Unauthenticated Remote Code Execution

The Hacker News · 20 Oct 2026

Cybersecurity researchers have released a proof-of-concept (PoC) exploit for a recently patched critical security flaw impacting Fortinet FortiSIEM that could result in arbitrary code execution. The vulnerability, tracked as CVE-2026-106173 (CVSS score: 9.4), is a critical path traversal flaw that could allow an unauthenticated attacker to execute unauthorized code or commands via specially

Recent mention · Horizon3.ai Attack Research

CVE-2026-106173 Deep-Dive: FortiSIEM gRPC Path Traversal File Write RCE

Horizon3.ai Attack Research · 20 Oct 2026

Horizon3 researchers analyze CVE-2026-106173, a critical Fortinet FortiSIEM vulnerability affecting an unauthenticated gRPC service. The deep-dive explains how path traversal and null-byte handling enable arbitrary file writes and remote code execution, along with indicators of compromise for defenders.

Recent mention · FortiGuard

Arbitrary file write in grpc phQueryMaster

FortiGuard · 13 Oct 2026

CVSSv3 Score: 9.4 An Improper limitation of a pathname to a restricted directory ('path traversal') [CWE-22] in FortiSIEM may allow an unauthenticated attacker to execute unauthorized code or commands via specially crafted packets. Revised on 2026-10-13 00:00:00

Potential Proof of Concepts

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

horizon3ai/CVE-2026-106173

github · Created 2026-10-20 12:29:09 UTC · 0 stars · AI assessment 91%

Proof of concept exploit for CVE-2026-106173, a path traversal file write leading to RCE for Fortinet FortiSIEM

Timeline

From disclosure to observed exploitation

  1. 09:43 UTC

    Indicators of compromise added (2)

    Indicators of compromise recorded

  2. 09:43 UTC

    Observed by Previdian sensors

    Evidence-backed exploitation signal

  3. 12:29 UTC

    Public PoC available

    Public proof-of-concept code published

  4. 19:20 UTC

    Added to the Previdian watchlist

    Pro and Enterprise Watch users had 1 week of early warning before Previdian confirmed it as a KEV.

  5. 17:37 UTC

    CVE published

    Vulnerability disclosed publicly

  6. 16:19 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.

Start 14-day Pro trial Read API docs
  • 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-2026-106173

Sample API response 
{
  "cve_id": "CVE-2026-106173",
  "confidence": "Confirmed",
  "cvss_score": 9.8,
  "cvss_estimated": false,
  "epss_score": 0.00459,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": true
  },
  "sensor_telemetry": { "attempts": 2, "sensors": 2 }
}