CyberSecBulletin
CVE-2023-39107NVD status: Modified

enterprise_client: Improper Link Resolution Before File Access

Published Updated By the CyberSecBulletin desk

CVE-2023-39107 is a critical-severity improper link resolution before file access vulnerability in enterprise_client from NoMachine, with a CVSS 3.1 base score of 9.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version v8.8.1 as the first without the flaw, so updating enterprise_client to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 1.22% chance of exploitation within 30 days, higher than 69% of scored CVEs.

Patch this week

Critical severity: a successful attack would have severe impact.

What to do

  1. Update enterprise_client to v8.8.1 or a later version.
  2. Update free_edition to v8.8.1 or a later version.
  3. Update Nomachine to 8.8.1 or a later version.
  4. Read the advisory on kb.nomachine.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.

Affected products and versions

VendorProductAffected versionsFixed in
Nomachineenterprise_clientbefore v8.8.1v8.8.1
Nomachinefree_editionbefore v8.8.1v8.8.1
NomachineNomachinebefore 8.8.18.8.1

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
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
NoneNo data is disclosed.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H. Scored by NVD.

Official description

An arbitrary file overwrite vulnerability in NoMachine Free Edition and Enterprise Client for macOS before v8.8.1 allows attackers to overwrite root-owned files by using hardlinks.

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

The underlying weakness: Improper Link Resolution Before File Access

The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.

How developers prevent this class of flaw

  • Follow the principle of least privilege when assigning access rights to entities in a software system. Denying access to a file can prevent an attacker from replacing that file with a link to a sensitive file. Ensure good compartmentalization in the system to provide protected areas that can be trusted.

More Improper Link Resolution Before File Access vulnerabilities (CWE-59)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: poc, automatable: yes, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Patches and release notes

Technical write-ups (may include proof of concept)

Recent Improper Link Resolution Before File Access vulnerabilities

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