CVE-2026-68166
In the Linux kernel, the following vulnerability has been resolved: userfaultfd: prevent registration of special VMAs Vova Tokarev says: userfaultfd allows registration on shadow stack VMAs. With userfaultfd access, you can register on the shadow stack, discard a page ... and inject a page with chosen return addresses via UFFDIO_COPY. Update vma_can_userfault() to reject VM_SHADOW_STACK. While on it, also reject VM_SPECIAL so that if a driver would implement vm_uffd_ops, it wouldn't be possible to register special VMAs with userfaultfd. Since VM_SPECIAL includes VM_DONTEXPAND which is set but hugetlb, exclude hugetlb VMAs from the check for VM_SPECIAL.
Affected versions
Linux kernel versions
6.6
and later are affected. Fixed in
6.6.153,
6.12.105,
6.18.44,
7.1.6,
7.2
and their respective stable series.
References
5 totalFrequently asked questions
-
What is CVE-2026-68166?
CVE-2026-68166 is a unscored severity Linux kernel vulnerability . It affects Linux kernel versions from 6.6 onward and has been patched in 6.6.153, 6.12.105, 6.18.44 and others. CVE-2026-68166 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
-
Is there a patch available for CVE-2026-68166?
Yes. CVE-2026-68166 has been patched. Fixed versions include 6.6.153, 6.12.105, 6.18.44 and others. If you are running Linux kernel 6.6 or later up to the fix versions, apply the relevant patch for your kernel branch.
-
Is CVE-2026-68166 actively exploited?
No. CVE-2026-68166 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.