KEV Intelligence

Vulnerability report

Active exploitation observed Confirmed confidence In CISA KEV

CVE-2023-20198

Cisco IOS XE Software

Cisco / Cisco IOS XE Software · 16.1.1

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Severity
CVSS 10.0 · Critical
Confidence
Confirmed
Exploit status
Observed in sensors
EPSS
99.6%
First observed
12 Jun 2026
Last observed
15 Aug 2026

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2023-20198 is an unauthenticated vulnerability affecting Cisco Cisco IOS XE Software. Cisco is providing an update for the ongoing investigation into observed exploitation of the web UI feature in Cisco IOS XE...

Is it exploited?

Yes. KEV Intelligence sensors observed exploitation attempts with confirmed confidence.

Who is affected?

Cisco / Cisco IOS XE Software 16.1.1.

What should we do?

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

Overview

Cisco IOS XE Software

Cisco is providing an update for the ongoing investigation into observed exploitation of the web UI feature in Cisco IOS XE Software. We are updating the list of fixed releases and adding the Software Checker. Our investigation has determined that the actors exploited two previously unknown issues. The attacker first exploited CVE-2023-20198 to gain initial access and issued a privilege 15 command to create a local user and password combination. This allowed the user to log in with normal user access.

The attacker then exploited another component of the web UI feature, leveraging the new local user to elevate privilege to root and write the implant to the file system. Cisco has assigned CVE-2023-20273 to this issue. CVE-2023-20198 has been assigned a CVSS Score of 10.0. CVE-2023-20273 has been assigned a CVSS Score of 7.2. Both of these CVEs are being tracked by CSCwh87343.

Vendor Product Affected Status
Cisco Cisco IOS XE Software 16.12.6 Affected
Cisco Cisco IOS XE Software 16.12.1z1 Affected
Cisco Cisco IOS XE Software 16.12.5a Affected
Cisco Cisco IOS XE Software 16.12.5b Affected
Cisco Cisco IOS XE Software 16.12.1z2 Affected
Cisco Cisco IOS XE Software 16.12.6a Affected
Cisco Cisco IOS XE Software 16.12.7 Affected
Cisco Cisco IOS XE Software 16.12.9 Affected
Cisco Cisco IOS XE Software 16.12.10 Affected
Cisco Cisco IOS XE Software 17.1.1 Affected
Cisco Cisco IOS XE Software 17.1.1a Affected
Cisco Cisco IOS XE Software 17.1.1s Affected
Cisco Cisco IOS XE Software 17.1.1t Affected
Cisco Cisco IOS XE Software 17.1.3 Affected
Cisco Cisco IOS XE Software 17.2.1 Affected
Cisco Cisco IOS XE Software 17.2.1r Affected
Cisco Cisco IOS XE Software 17.2.1a Affected
Cisco Cisco IOS XE Software 17.2.1v Affected
Cisco Cisco IOS XE Software 17.2.2 Affected
Cisco Cisco IOS XE Software 17.2.3 Affected
Cisco Cisco IOS XE Software 17.3.1 Affected
Cisco Cisco IOS XE Software 17.3.2 Affected
Cisco Cisco IOS XE Software 17.3.3 Affected
Cisco Cisco IOS XE Software 17.3.1a Affected
Cisco Cisco IOS XE Software 17.3.1w Affected
Published
16 Oct 2023
Exploitation Reported
16 Oct 2023
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

Tags

edge nuclei_scanner ios nessus_scanner metasploit cisa

CVE References

Exploitation evidence

Why KEV Intelligence 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

CISA

Recorded 16 Oct 2023

Independent exploitation attestation added to the KEV Intelligence record.

Active exploitation observed

KEV Intelligence sensor

First observed 12 Jun 2026

First-party sensor telemetry confirms matching exploitation attempts.

Proof of concept available

GitHub

Recorded 17 Oct 2023

Public scanner or PoC coverage increases practical exploitability.

Known exploited vulnerability sources

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

Learn about Pro API access
Source Added
CISA First 2023-10-16 00:00 UTC
The Shadowserver 2026-06-01 00:00 UTC
Tenable Blog 2026-06-02 14:20 UTC
KEV Intelligence 2026-07-07 13:59 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.

12

Attempts observed

4

Unique attacker IPs

4

Attacker countries

GB · JP · SC · US

8

Sensors observed

Exploitation attempts over the last 70 days

Daily events observed by KEV Intelligence sensors

Updated 19 Aug 2026

0
3
0
0
0
0
0
0
0
0
3
0
0
0
0
0
3
0
6
3
0
0
48
0
0
0
4
0
0
1
0
0
0
12
2
0
2
8
4
0
1
1
3
0
0
0
0
0
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3
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0
11 Jun 25 Jun 9 Jul 23 Jul 19 Aug

First observed 12 Jun 2026 · Last observed 15 Aug 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
3
User-Agents
2

Raw values available in Pro and Enterprise.

Virtual patch status

No KEV Intelligence 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
Metasploit https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/linux/misc/cisco_ios_xe_rce.rb 28 Apr 2025
Nuclei https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2023/CVE-2023-20198.yaml 25 Apr 2025
Nessus https://www.tenable.com/plugins/nessus/184452 06 Nov 2023

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

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

EPSS

99.6%

Weaknesses

Unprotected Alternate Channel CWE-420

Recent mention · Tenable Blog

Inside the customer environment: Where threat actors, vulnerabilities, and exposed assets intersect

Tenable Research has developed a graph-based model linking 600+ threat groups to real-world customer exposures. It reveals which vulnerabilities sit at the intersection of severity, active exploitation, and organizational risk.Key takeawaysThe "patch everything" strategy is...

Read full advisory

All Mentions

Recent mention · Tenable Blog

Inside the customer environment: Where threat actors, vulnerabilities, and exposed assets intersect

Tenable Blog · 27 May 2026

Tenable Research has developed a graph-based model linking 600+ threat groups to real-world customer exposures. It reveals which vulnerabilities sit at the intersection of severity, active exploitation, and organizational risk.Key takeawaysThe "patch everything" strategy is dead: Vulnerability prioritization based on exploitation risk offers a path forward. A directed graph model linking 600+ threat actors to vulnerabilities in 7,800 customer environments reveals that 68% of organizations carry at least one CVE previously exploited by a named adversary, and 321 tracked threat groups can...

Recent mention · TheHackerNews

China-linked Salt Typhoon Exploits Critical Cisco Vulnerability to Target Canadian Telecom

TheHackerNews · 24 Jun 2025

The Canadian Centre for Cyber Security and the U.S. Federal Bureau of Investigation (FBI) have issued an advisory warning of cyber attacks mounted by the China-linked Salt Typhoon actors to breach major global telecommunications providers as part of a cyber espionage campaign. The attackers exploited a critical Cisco IOS XE software (CVE-2023-20198, CVSS score: 10.0) to access configuration

Recent mention · Tenable Blog

Cybersecurity Snapshot: U.K. NCSC’s Best Cyber Advice on AI Security, the Quantum Threat, API Risks, Mobile Malware and More

Tenable Blog · 09 May 2025

In this special edition of the Cybersecurity Snapshot, we bring you some of the most valuable guidance offered by the U.K. National Cyber Security Centre (NCSC) in the past 18 months. Check out best practices, recommendations and insights on protecting your AI systems, APIs and mobile devices, as well as on how to prep for post-quantum cryptography, and more.In case you missed it, here are six NCSC recommendations to help your organization fine-tune its cybersecurity strategy and operations.1 - How to migrate to quantum-resistant cryptographyIs your organization planning to adopt...

Potential Proof of Concepts

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

Cisco IOS XE Web UI - Command Injection

nuclei · Created Unknown

Timeline

From disclosure to observed exploitation

  1. Public PoC available

    Public proof-of-concept code published

  2. Observed by KEV Intelligence sensors

    Evidence-backed exploitation signal

  3. Indicators of compromise added (12)

    Indicators of compromise recorded

  4. KEV confirmed by Tenable Blog

    Exploitation attested by an external source

  5. KEV confirmed by The Shadowserver

    Exploitation attested by an external source

  6. Metasploit module available

    Exploit module available

  7. Nuclei template available

    Scanner coverage available

  8. Nessus plugin available

    Scanner coverage available

  9. CVE published

    Vulnerability disclosed publicly

  10. Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  11. 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-2023-20198

Free JSON includes basic KEV fields 
{
  "cve_id": "CVE-2023-20198",
  "confidence": "Confirmed",
  "cvss_score": 10.0,
  "cvss_estimated": false,
  "epss_score": 0.99571,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": true
  },
  "sensor_telemetry": { "attempts": 12, "sensors": 8 }
}

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