Number: AL26-009
Date: April 30, 2026
Audience
This Alert is intended for IT professionals and managers.
Purpose
An Alert is used to raise awareness of a recently identified cyber threat that may impact cyber information assets, and to provide additional detection and mitigation advice to recipients. The Canadian Centre for Cyber Security (Cyber Centre) is also available to provide additional assistance regarding the content of this Alert upon request.
Details
The Cyber Centre is aware of a security vulnerability affecting Linux-based operating systems, identified as CVE-2026-31431Footnote 1.
Tracked as CVE-2026-31431, this vulnerability is an Incorrect Resource Transfer Between Spheres vulnerability (CWE-669)Footnote 2, a weakness that may allow resources or privileges to be improperly transferred between security domains.
Public reporting and Linux kernel security advisoriesFootnote 3Footnote 4Footnote 5Footnote 6Footnote 7 indicate that this vulnerability originates in the Linux kernel and may, under certain conditions, allow privilege escalation to root or bypass of isolation mechanismsFootnote 8Footnote 9.
Chained with a remote code execution vulnerability, this vulnerability is even more significant and needs to be prioritized for patching.
Suggested actions
The Cyber Centre recommends that organizations identify and remediate affected systems as soon as possible.
Affected environments include, but are not limited to:
- Enterprise Linux distributions (Red Hat Enterprise Linux, Rocky Linux, AlmaLinux, Oracle Linux);
- Debian-based distributions (Debian, Ubuntu);
- SUSE-based distributions (SUSE Linux Enterprise, openSUSE);
- Other Linux systems running vulnerable kernel versions.
Organizations should consult their respective distribution maintainers for version-specific impact and patching guidance. Organizations can determine whether systems may be affected by CVE-2026-31431 in:
- Identifying the running Linux kernel version using the uname -r command;
- Reviewing distribution-specific security advisories, noting that fixes may be backported without visible version changesFootnote 8Footnote 9;
- Assessing exposure on systems that allow local users, host containerized workloads, or execute untrusted code;
- Verifying that vendor-provided kernel or security updates are installed and in use, and rebooting systems if required.
In addition to applying vendor patches, the Cyber Centre recommends that organizations:
- Reboot systems after kernel updates to ensure fixes are fully applied;
- Restrict local and remote access to affected systems, particularly in shared or multi-tenant environments;
- Enforce kernel-level security controls such as SELinux, AppArmor, and seccomp where supported;
- Review and limit administrative privileges, including sudo and role-based access;
- Monitor authentication, system, and kernel logs for signs of privilege escalation or abnormal activity;
- Isolate high-risk or Internet-facing workloads using segmentation or containment technologies.
In addition, the Cyber Centre strongly recommends that organizations review and implement the Cyber Centre’s Top 10 IT Security Actions with an emphasis on the following topicsFootnote 10.
- Patch operating systems and applications
- Enforce the management of administrative privileges
- Harden operating systems and applications
- Segment and separate information
Should activity matching the content of this alert be discovered, recipients are encouraged to report via My Cyber Portal or email contact@cyber.gc.ca.
