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CVE-2026-68166

Unknown

Last modified

CVE-2026-68166 is a vulnerability of currently unknown severity. 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 ...

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.

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
LinuxLinux>= 54007f818206dc27309ca423df4c87dd160a7208, < 165613191ad9d034bf17c00e3a142f9561597ec5; >= 54007f818206dc27309ca423df4c87dd160a7208, < 0c26202b157f1efc3cd2f26f5c30f59b508a6a5d; >= 54007f818206dc27309ca423df4c87dd160a7208, < 3c58f641e813c3c71039f8fd4d4e2a3aab713288
LinuxLinux6.6

References

Timeline

Published
Last Modified
Status
Received

Frequently Asked Questions

What is 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.
How severe is CVE-2026-68166?
Severity scoring for CVE-2026-68166 is pending analysis.
How do I fix CVE-2026-68166?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST