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Actively exploited

CVE-2022-26143 MiCollab, MiVoice Business Express Access Control Vulnerability

A vulnerability has been identified in MiCollab and MiVoice Business Express that may allow a malicious actor to gain unauthorized access to sensitive information and services, cause performance degradations or a denial of service condition on the affected system.

From the CISA KEV catalogue version 2026.11.06, with Cybergen analysis. Updated 6 Nov 2026.

Our Assessment

Should You Worry?

Patch nowCybergen assessment
  • CISA confirmed exploitation in the wild and added it to the Known Exploited Vulnerabilities catalogue on 25 Mar 2022.
  • Rated Critical severity (CVSS 9.8, scored by CISA).
  • It has been in the catalogue for 1,687 days. Systems still unpatched now have almost certainly been scanned for it.
The Vulnerability

What It Is

The TP-240 (aka tp240dvr) component in Mitel MiCollab before 9.4 SP1 FP1 and MiVoice Business Express through 8.1 allows remote attackers to obtain sensitive information and cause a denial of service (performance degradation and excessive outbound traffic). This was exploited in the wild in February and March 2022 for the TP240PhoneHome DDoS attack.

From Watch to Action

What To Do Now

  1. 1

    Find it

    Search your asset inventory and external attack surface for Mitel MiCollab, MiVoice Business Express. Include cloud images, appliances and anything a supplier runs for you.

    Attack Surface Management
  2. 2

    Fix it

    Apply updates per vendor instructions.

    Vulnerability Management
  3. 3

    Hunt for compromise

    If an affected system was reachable before you patched, assume it may have been hit. Check logs, new accounts, web shells and outbound connections from the date of exposure.

    Incident Response
  4. 4

    Prove it is fixed

    Rescan or test the system after patching. Upgrades that fail silently and forgotten secondary instances are common.

    Penetration Testing

Vendor Advisories

Regulation

The Compliance Clock

Cyber EssentialsRated critical, so if it affects devices in your Cyber Essentials scope, the update must be installed within 14 days of the vendor releasing it.NIS2If exploitation causes a significant incident, essential and important entities owe their CSIRT an early warning within 24 hours and a notification within 72 hours.DORAFinancial entities must classify ICT incidents and send an initial notification for a major incident within strict deadlines, with exploited flaws a common cause.US federal (BOD 22-01)Federal civilian agencies had until 15 Apr 2022 to remediate. A sensible benchmark for everyone else.

General guidance, not legal advice. Your obligations depend on your sector, scope and jurisdiction.

Stay Ahead

More Exploited Mitel Flaws

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CVE-2024-41710Mitel SIP Phones Argument Injection VulnerabilityAdded 12 Feb 2025CVE-2024-55550 · RansomwareMitel MiCollab Path Traversal VulnerabilityAdded 7 Jan 2025CVE-2024-41713 · RansomwareMitel MiCollab Path Traversal VulnerabilityAdded 7 Jan 2025CVE-2022-41223 · RansomwareMitel MiVoice Connect Code Injection VulnerabilityAdded 21 Feb 2023CVE-2022-40765 · RansomwareMitel MiVoice Connect Command Injection VulnerabilityAdded 21 Feb 2023CVE-2022-29499 · RansomwareMitel MiVoice Connect Data Validation VulnerabilityAdded 27 Jun 2022

All 7 exploited Mitel vulnerabilities

Not Sure If You Are Exposed?

Our attack surface and vulnerability teams can check your internet-facing estate for CVE-2022-26143 and every other exploited flaw on the list.

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Evidence

Sources

  1. CISA Known Exploited Vulnerabilities catalogue
  2. NVD: CVE-2022-26143
  3. CVE record: CVE-2022-26143
  4. FIRST EPSS
  5. mitel.com/en-ca/support/security-advisories/mitel-product-security-advisory-22-0001
  6. akamai.com/blog/security/phone-home-ddos-attack-vector
  7. shadowserver.org/news/cve-2022-26143-tp240phonehome-reflection-amplification-ddos-attack-vector/
  8. news.ycombinator.com/item?id=30614073
  9. blog.cloudflare.com/cve-2022-26143/
  10. team-cymru.com/blog/2022/03/08/record-breaking-ddos-potential-discovered-cve-2022-26143/
  11. arstechnica.com/information-technology/2022/03/ddosers-use-new-method-capable-of-amplifying-traffic-