High Privilege escalation

CVE-2026-15226 — snapd snap-confine Sandbox Confinement Bypass via Omission of setuid Restriction in Seccomp Templates

A sandbox confinement bypass vulnerability exists in Canonical snapd within its internal execution environment compiler (snap-confine). The default seccomp security templates generated by the engine to restrict system calls do not filter or reject process operations capable of creating or manipulating file execution flags with set-user-ID attributes. Consequently, an application running within a strictly confined snap environment can successfully compile or drop binaries and apply setuid properties to them. If a compromised or malicious process inside the snap sandbox executes these generated setuid binaries, it can potentially circumvent architectural sandboxing assumptions, drop intended restriction policies, or execute privileged actions inside the container namespace that should otherwise be strictly blocked. The vulnerability has been resolved by hardening the seccomp template engine to block the execution and creation of setuid executables by sandboxed snap processes.

Published Jul 21, 2026 · Updated Oct 15, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: canonical

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.2% (30-day exploitation probability)+1
Technical severity (high)+6

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.18%

ahead of 7% of scored CVEs · Oct 15, 2026

Affects

Canonical

Ubuntu 16.04 LTS and 5 more

CVSS base

8.4

High · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

None

none · proof-of-concept · active

Automatable

can an attacker script the kill-chain steps

Technical impact

Total

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Canonical Ubuntu 16.04 LTS, Canonical Ubuntu 18.04 LTS, Canonical Ubuntu 20.04 LTS…).
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes matching the vulnerability class (privilege escalation), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Canonical	Ubuntu 16.04 LTS	versions not specified by the source	Vulnerable	CVE Program (cve.org) e CISA ADP
Canonical	Ubuntu 18.04 LTS	versions not specified by the source	Vulnerable	CVE Program (cve.org) e CISA ADP
Canonical	Ubuntu 20.04 LTS	versions not specified by the source	Vulnerable	CVE Program (cve.org) e CISA ADP
Canonical	Ubuntu 22.04 LTS	versions not specified by the source	Vulnerable	CVE Program (cve.org) e CISA ADP
Canonical	Ubuntu 24.04 LTS	versions not specified by the source	Vulnerable	CVE Program (cve.org) e CISA ADP
Canonical	Ubuntu 26.04 LTS	versions not specified by the source	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Local

Attack complexity

Low

Privileges required

Low

User interaction

None

Scope

Changed

Confidentiality

High

Integrity

High

Availability

None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
8.4	CVSS 3.1	High	2.0	5.8	security@ubuntu.com via NIST National Vulnerability Database
8.4	CVSS 3.1	High	—	—	canonical via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N (score shown at the top: security@ubuntu.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-250 · Execution with Unnecessary Privileges

Other CVEs with this weakness →

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.

endpoint telemetry (EDR)

Timeline

What happened to this CVE, newest first.

2026
Affected products added · canonical/ubuntu 26.04 lts, canonical/ubuntu 24.04 lts, canonical/ubuntu 22.04 lts, canonical/ubuntu 20.04 lts, canonica
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 15, 2026
CVSS changed · 8.4
Oct 15, 2026 · NIST National Vulnerability Database
Source status changed · → Awaiting Analysis
Oct 15, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 15, 2026 · NIST National Vulnerability Database
CVE published
Jul 21, 2026 · canonical

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

1 on the record

ubuntu.com/security/CVE-2026-15226
vdb-entry, issue-tracking, NIST National Vulnerability Database

Elsewhere on this site

Canonical
every CVE for this vendor

Privilege escalation
same class

CWE-250
other pages naming this weakness

Related CVEs (same products)

High CVE-2026-8933 snap-confine Local Privilege Escalation via Capabilities Misconfiguration or Flaw in Execution Environment Setup Jul 21, 2026
Medium CVE-2024-5300 AppArmor Base Profile Misconfiguration in snapd Permits Confined Snaps Unauthorized Access to Hashed Passwords via systemd-userdbd Jul 21, 2026
Medium CVE-2026-9494 ubuntu-pro-client Information Disclosure via Cleartext Bearer Token Exposure in Process Command Line Jul 16, 2026
Critical CVE-2026-11386 ubuntu-pro-client Input Validation Vulnerability Leading to Arbitrary APT Directive Injection and Remote Code Execution Jul 16, 2026
Medium CVE-2026-12391 ubuntu-pro-client Local Privilege Escalation and Information Disclosure via Symlink Arbitrary File Read in collect-logs Jul 16, 2026
Critical CVE-2026-12249 Canonical ADSys plaintext HTTP CA certificate retrieval enables trust store poisoning Jun 22, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No fixed version, patch or mitigation documented.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-15226 is "snapd snap-confine Sandbox Confinement Bypass via Omission of setuid Restriction in Seccomp Templates", rated High. It affects Ubuntu 16.04 LTS (Canonical); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 8.4 describes technical severity. EPSS 0.18% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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