Vulnerability Description
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.
References
- https://git.kernel.org/stable/c/0c26202b157f1efc3cd2f26f5c30f59b508a6a5d
- https://git.kernel.org/stable/c/165613191ad9d034bf17c00e3a142f9561597ec5
- https://git.kernel.org/stable/c/3c58f641e813c3c71039f8fd4d4e2a3aab713288
- https://git.kernel.org/stable/c/495a28d5a100be1b232633f4c2dcc42ba10b3796
- https://git.kernel.org/stable/c/d974b4b786214883bd8e56bda10b454c80fd6205
FAQ
What is CVE-2026-68166?
CVE-2026-68166 is a documented vulnerability. 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. Wit...
How severe is CVE-2026-68166?
CVSS scoring is not yet available for CVE-2026-68166. Check NVD for updates.
Is there a patch for CVE-2026-68166?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.