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Actively exploited

CVE-2019-18988 TeamViewer Desktop Bypass Remote Login Vulnerability

TeamViewer Desktop allows for bypass of remote-login access control because the same AES key is used for different customers' installations. If an attacker were to know this key, they could decrypt protected information stored in registry or configuration files or decryption of the Unattended Access password to the system (which allows for remote login to the system).

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

Our Assessment

Should You Worry?

Patch urgentlyCybergen assessment
  • CISA confirmed exploitation in the wild and added it to the Known Exploited Vulnerabilities catalogue on 3 Nov 2021.
  • Rated High severity (CVSS 7.0, scored by CISA).
  • It has been in the catalogue for 1,829 days. Systems still unpatched now have almost certainly been scanned for it.
The Vulnerability

What It Is

TeamViewer Desktop through 14.7.1965 allows a bypass of remote-login access control because the same key is used for different customers' installations. It used a shared AES key for all installations since at least as far back as v7.0.43148, and used it for at least OptionsPasswordAES in the current version of the product. If an attacker were to know this key, they could decrypt protect information stored in the registry or configuration files of TeamViewer. With versions before v9.x , this allowed for attackers to decrypt the Unattended Access password to the system (which allows for remote login to the system as well as headless file browsing). The latest version still uses the same key for OptionPasswordAES but appears to have changed how the Unattended Access password is stored. While in most cases an attacker requires an existing session on a system, if the registry/configuration keys were stored off of the machine (such as in a file share or online), an attacker could then decrypt the required password to login to the system.

From Watch to Action

What To Do Now

  1. 1

    Find it

    Search your asset inventory and external attack surface for TeamViewer Desktop. 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 high, 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 3 May 2022 to remediate. A sensible benchmark for everyone else.

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

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Evidence

Sources

  1. CISA Known Exploited Vulnerabilities catalogue
  2. NVD: CVE-2019-18988
  3. CVE record: CVE-2019-18988
  4. FIRST EPSS
  5. community.teamviewer.com/t5/Knowledge-Base/tkb-p/Knowledgebase?threadtype=label&labels=Security
  6. whynotsecurity.com/blog/teamviewer/
  7. twitter.com/Blurbdust/status/1224212682594770946?s=20
  8. community.teamviewer.com/t5/Announcements/Specification-on-CVE-2019-18988/td-p/82264