CyberSecBulletin
CVE-2026-16444NVD status: Deferred

Full Client, Host, QuickSupport & Portable: External Control of File Name or Path

Published Updated By the CyberSecBulletin desk

CVE-2026-16444 is a high-severity external control of file name or path vulnerability in Full Client, Host, QuickSupport & Portable from TeamViewer, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. The record lists version 15.81.5 as the first without the flaw, so updating Full Client, Host, QuickSupport & Portable to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.41% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Full Client, Host, QuickSupport & Portable to 15.81.5 or a later version.
  2. Update Full Client, Host, QuickSupport & Portable (for Windows 7 & 8) to 15.64.7 or a later version.
  3. Update Full Client, Host, QuickSupport (v14 for Windows) to 14.7.48833 or a later version.
  4. Read the advisory on teamviewer.com for workarounds and exact fixed builds.
  5. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
  6. Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.

Affected products and versions

VendorProductAffected versionsFixed in
TeamViewerFull Client, Host, QuickSupport & Portable15.0 up to, but not including, 15.81.515.81.5
TeamViewerFull Client, Host, QuickSupport & Portable (for Windows 7 & 8)15.64.0 up to, but not including, 15.64.715.64.7
TeamViewerFull Client, Host, QuickSupport (v14 for Windows)14.0 up to, but not including, 14.7.4883314.7.48833
TeamViewerFull Client, Host, QuickSupport (v14 for Linux)14.0 up to, but not including, 14.7.4883814.7.48838
TeamViewerFull Client, Host, QuickSupport (v14 for macOS)14.0 up to, but not including, 14.7.4883814.7.48838
TeamViewerFull Client, Host, QuickSupport & Portable (v13 for Windows)13.0 up to, but not including, 13.2.3622913.2.36229
TeamViewerFull Client, Host, QuickSupport (v13 for Linux)13.0 up to, but not including, 13.2.15397813.2.153978
TeamViewerFull Client, Host, QuickSupport (v13 for macOS)13.0 up to, but not including, 13.2.15398113.2.153981

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
HighSuccess depends on conditions outside the attacker's control.
Privileges required
NoneNo account or login is needed.
User interaction
RequiredA user must take an action such as opening a file or link.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H. Scored by CNA (teamviewer.com).

Official description

Improper neutralization of path traversal sequences in TeamViewer Desktop Clients prior Version 15.81.5 allows an authenticated remote session participant to write files to unintended locations on the local file system via file transfer or virtual file clipboard mechanisms. An attacker can leverage this behavior to achieve arbitrary file write and potentially execute code with the privileges of the affected user.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: External Control of File Name or Path

The product allows user input to control or influence paths or file names that are used in filesystem operations.

How developers prevent this class of flaw

  • When the set of filenames is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames, and reject all other inputs. For example, ID 1 could map to inbox.txt and ID 2 could map to profile.txt. Features such as the ESAPI AccessReferenceMap provide this capability.
  • Run your code in a jail or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict all access to files within a particular directory. Examples include the Unix chroot jail and AppArmor. In general, managed code may provide some protection. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of your application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails.
  • For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.

More External Control of File Name or Path vulnerabilities (CWE-73)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent External Control of File Name or Path vulnerabilities

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