CyberSecBulletin
CVE-2026-3888NVD status: Analyzed

Ubuntu 16.04 LTS: Privilege Chaining

Published Updated By the CyberSecBulletin desk

CVE-2026-3888 is a high-severity privilege chaining vulnerability in Ubuntu 16.04 LTS from Canonical, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. There is no confirmed exploitation so far. EPSS estimates a 1.43% chance of exploitation within 30 days, higher than 73% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Check which version of Ubuntu 16.04 LTS you run against the affected versions below, and install the vendor's latest release.

Affected products and versions

VendorProductAffected versionsFixed in
CanonicalUbuntu 16.04 LTSNot specified in the recordNot stated
CanonicalUbuntu 18.04 LTSNot specified in the recordNot stated
CanonicalUbuntu 20.04 LTSNot specified in the recordNot stated
CanonicalUbuntu 22.04 LTSNot specified in the recordNot stated
CanonicalUbuntu 24.04 LTSNot specified in the recordNot stated
CanonicalUbuntu Linux16.04; 18.04; 20.04; 22.04; 24.04Not stated

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
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
HighSuccess depends on conditions outside the attacker's control.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
ChangedThe attack can reach beyond the vulnerable component into other systems.
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:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H. Scored by CNA (ubuntu.com).

Official description

Local privilege escalation in snapd on Linux allows local attackers to get root privilege by re-creating snap's private /tmp directory when systemd-tmpfiles is configured to automatically clean up this directory. This issue affects Ubuntu 16.04 LTS, 18.04 LTS, 20.04 LTS, 22.04 LTS, and 24.04 LTS.

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

The underlying weakness: Privilege Chaining

Two distinct privileges, roles, capabilities, or rights can be combined in a way that allows an entity to perform unsafe actions that would not be allowed without that combination.

How developers prevent this class of flaw

  • Consider following the principle of separation of privilege. Require multiple conditions to be met before permitting access to a system resource.
  • Very carefully manage the setting, management, and handling of privileges. Explicitly manage trust zones in the software.
  • Run your code using the lowest privileges that are required to accomplish the necessary tasks. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.

More Privilege Chaining vulnerabilities (CWE-268)

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

Third-party and government advisories

Other vulnerabilities in Ubuntu 16.04 LTS

All Ubuntu 16.04 LTS vulnerabilities

Recent Privilege Chaining vulnerabilities

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