CVE Catalog

CVE-2026-68166

Low risk· EPSS 10%
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.20%

10th percentile - higher than 10% of all known CVEs

Summary

In the Linux kernel, the vma_can_userfault() function did not reject registration of shadow stack and VM_SPECIAL VMAs, allowing registration of special memory areas via userfaultfd. The fix adds rejection of VM_SHADOW_STACK and VM_SPECIAL, except for hugetlb VMAs.

Risk Assessment

The risk includes the possibility of using userfaultfd to manipulate the shadow stack and inject return addresses, which may lead to control flow hijacking.

Recommendation

It is recommended to update the Linux kernel to a version containing the fix that prevents registration of special VMAs via userfaultfd.

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

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.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS