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Run uname -r to see the kernel release currently running, then check your distribution’s security advisories and package updates for your exact Linux release. The version string alone cannot tell you whether the system is patched: distributions may backport security fixes without adopting the newest upstream version. After installing a kernel update, you may also need to reboot before the system is running it.
1. Check the kernel currently running
Open a terminal and run:
uname -rThis prints the release of the kernel that is booted now. Keep the full output, including any distribution suffix. Do not treat it as a complete security status: it identifies the running kernel, not whether it contains a particular fix or whether a newer kernel package is installed.
Distribution kernels can be modified from upstream kernel.org releases. Kernel.org advises users of distribution-supplied kernels to use the distribution’s channels for version and support questions (Kernel.org FAQ). Its security-bug guidance also notes that the version identifiers of distro kernels are not meaningful to upstream maintainers in that context; that guidance concerns reporting bugs to the upstream kernel project, not whether a vendor’s kernel is secure (Linux kernel security-bug documentation).
2. Identify your distribution and release
Before interpreting an update result, establish which distribution and release you are using. A widely available first check is:
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cat /etc/os-releaseLook for fields such as ID, NAME, and VERSION_ID. If the file is unavailable or your system uses a different setup, use its system-information utility or consult its administrator. Keep the release identifier alongside the output of uname -r.
Update commands, package names, support periods, enabled repositories, and advisory formats vary between distributions and releases. Do not apply Ubuntu commands to a different distribution or assume that an empty package-update result means a system is supported and fully patched.
3. Check the distribution’s security status
Use the security advisory and package-management channel for the distribution and release you identified. The key questions are whether that release is still supported, whether its relevant repositories are enabled, and whether the vendor marks the kernel package as affected or fixed.
Ubuntu
Ubuntu’s security documentation explains that security updates for supported releases can include patches backported to the distribution’s packages. As a result, an Ubuntu kernel may have an older-looking upstream version and still include a vendor fix. Compare the installed package with Ubuntu’s release-specific security information rather than judging it against the newest upstream kernel number (Ubuntu security updates).
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Ubuntu may notify desktop users about updates and show server notifications through the message of the day (MOTD). It also documents unattended security updates. Check that your particular release and package are covered, and consult Ubuntu’s current support information for the relevant release and component; support scope depends on those details.
Red Hat Enterprise Linux
For RHEL, use the security advisories and DNF procedures applicable to your RHEL release. Red Hat’s documentation covers security updates and advisory workflows, but access to the relevant repositories can depend on the system’s subscription and repository configuration. Confirm those prerequisites before interpreting the package manager’s results (Red Hat Enterprise Linux 9 security-update documentation).
Other distributions
For Debian, Fedora, or another distribution, use that project’s official security tracker, advisories, and supported package manager for the exact release. Do not infer a command, support status, or patch policy from the Ubuntu or RHEL examples above.
4. Apply updates through the supported mechanism
Install available security updates using the distribution’s documented package manager or update interface. Check that the system is receiving updates from the repositories intended for its release and that the release remains within its support scope. A generic “no updates available” message is not proof of security if the required repository is disabled, unavailable, or the release is out of support.
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Kernel.org’s threat-model guidance places responsibility on administrators to keep systems up to date and says outdated kernels, particularly end-of-life branches, are outside that threat model (Linux kernel threat model). For distro kernels, use the vendor’s instructions to determine what “up to date” means for that distribution and release.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.5. Confirm whether the updated kernel is running
Installing a new kernel package does not replace the kernel already loaded in memory. After an update, run uname -r again. If it still reports the previous release, the system has not booted into the newly installed kernel.
Follow the vendor’s restart instructions for the update or advisory. On RHEL, the needs-restarting utility can provide a reboot hint, and Red Hat documents restart guidance alongside security-update procedures. Treat the advisory’s package-specific guidance as authoritative rather than relying on a generic hint alone (Ubuntu manpage for needs-restarting; Red Hat security-update documentation).
Where Livepatch fits
Ubuntu Livepatch can cover selected high- and critical-severity kernel vulnerabilities, but Canonical says it does not eliminate the need to reboot when upgrading to a newer kernel. Enabling Livepatch also does not turn on APT security updates, so it is not a substitute for the normal update process (Ubuntu Livepatch: Do I need to reboot?).
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Do not decide exposure from the CVE number or upstream version alone. Check the distribution’s advisory for your exact release and kernel package, then consider whether the affected feature or configuration applies to your system. Kernel.org notes that CVE applicability depends on the system and use case, and that distro-specific kernel issues may need to be handled by the distribution (Linux kernel CVE guidance).
Quick Recap
- Running version:
uname -rtells you which kernel is booted. - Distribution context:
/etc/os-releasehelps identify which vendor guidance applies. - Patch status: Check release-specific vendor advisories and package updates, not just upstream version comparisons.
- Reboot status: Verify that the updated kernel is running when the vendor requires a reboot.
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