PatchSiren cyber security CVE debrief

CVE-2026-3888 Canonical CVE debrief

CVE-2026-3888 is a local privilege escalation vulnerability in snapd on Linux systems. The vulnerability allows local attackers to gain root privileges by re-creating snap's private /tmp directory when systemd-tmpfiles is configured to automatically clean up this directory. This issue affects multiple versions of Ubuntu, including 16.04 LTS, 18.04 LTS, 20.04 LTS, 22.04 LTS, and 24.04 LTS.

Vendor: Canonical
Product: Ubuntu 16.04 LTS
CVSS: HIGH 7.8
CISA KEV: Not listed in stored evidence
Original CVE published: 2026-03-17
Original CVE updated: 2026-06-04
Advisory published: 2026-03-17
Advisory updated: 2026-06-04

Who should care

System administrators and users of Ubuntu 16.04 LTS, 18.04 LTS, 20.04 LTS, 22.04 LTS, and 24.04 LTS who use snapd on Linux systems.

Technical summary

The vulnerability has a CVSS score of 7.8 and is classified as HIGH severity. The CVSS vector is CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H. The weakness associated with this vulnerability is CWE-268.

Defensive priority

High

Recommended defensive actions

Apply patches or updates provided by Canonical to address the vulnerability.
Review and adjust systemd-tmpfiles configurations to prevent exploitation.
Monitor systems for suspicious activity related to snapd and /tmp directory manipulation.

Evidence notes

Evidence from NVD and CVE.org confirms the vulnerability details and affected systems.

Sources and references

Verified primary and authoritative sources

CVE-2026-3888 CVE Program record
Publisher, destination, and source semantics verified

URL: https://www.cve.org/CVERecord?id=CVE-2026-3888

CVE Program - Official CVE Program record with source-provided CVE metadata.
CVE-2026-3888 NVD vulnerability detail
Publisher, destination, and source semantics verified

URL: https://nvd.nist.gov/vuln/detail/CVE-2026-3888

NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Mitigation or vendor reference
Unverified legacy reference

URL: https://blog.qualys.com/vulnerabilities-threat-research/2026/03/17/cve-2026-3888-important-snap-flaw-enables-local-privilege-escalation-to-root

[email protected] - Mitigation, Third Party Advisory
Mitigation or vendor reference
Unverified legacy reference

URL: https://cdn2.qualys.com/advisory/2026/03/17/snap-confine-systemd-tmpfiles.txt

[email protected] - Third Party Advisory
Mitigation or vendor reference
Unverified legacy reference

URL: https://discourse.ubuntu.com/t/snapd-local-privilege-escalation-cve-2026-3888

[email protected] - Mitigation, Third Party Advisory
Mitigation or vendor reference
Unverified legacy reference

URL: https://ubuntu.com/security/CVE-2026-3888

[email protected] - Third Party Advisory
Mitigation or vendor reference
Unverified legacy reference

URL: https://ubuntu.com/security/notices/USN-8102-1

[email protected] - Third Party Advisory

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.