CVE-2026-20199 — The SSL Certificate Handling Of Cisco ThousandEyes Virtual A Vulnerability
CVE-2026-20199 — A vulnerability in the SSL certificate handling of Cisco ThousandEyes Virtual Appliance could allow an authenticated, remote attacker to execute commands on the underlying operating system as the root user. This vulnerability is due to insufficient validation of user-supplied inp
What This Means For You
- If your environment is affected by CWE-74, review your exposure and prioritize patching based on your environment. Monitor vendor advisories for CVE-2026-20199 updates and patches.
Related ATT&CK Techniques
🛡️ Detection Rules
3 rules · 6 SIEM formats3 detection rules auto-generated for this incident, mapped to MITRE ATT&CK. Sigma YAML is free — export to any SIEM format via the Intel Bot.
CVE-2026-20199 - Cisco ThousandEyes Virtual Appliance Crafted Certificate Upload
title: CVE-2026-20199 - Cisco ThousandEyes Virtual Appliance Crafted Certificate Upload
id: scw-2026-05-20-ai-1
status: experimental
level: critical
description: |
Detects the specific action of uploading a certificate to a Cisco ThousandEyes Virtual Appliance, which is the initial step in exploiting CVE-2026-20199. This rule looks for POST requests to a common certificate upload endpoint that results in a successful status code.
author: SCW Feed Engine (AI-generated)
date: 2026-05-20
references:
- https://shimiscyberworld.com/posts/nvd-CVE-2026-20199/
tags:
- attack.initial_access
- attack.t1190
logsource:
category: webserver
detection:
selection:
cs-uri|contains:
- '/upload/certificate'
cs-method|exact:
- 'POST'
sc-status|exact:
- '200'
condition: selection
falsepositives:
- Legitimate administrative activity
Source: Shimi's Cyber World · License & reuse
Indicators of Compromise
| ID | Type | Indicator |
|---|---|---|
| CVE-2026-20199 | vulnerability | CVE-2026-20199 |
| CWE-74 | weakness | CWE-74 |
Written by SCW Vulnerability Desk
Source & Attribution
| Source Platform | NVD |
| Channel | National Vulnerability Database |
| Published | May 20, 2026 at 20:16 UTC |
This content was curated and summarized by Shimi's Cyber World for informational purposes. It is not copied or republished in full. All intellectual property rights remain with the original author and source.
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