CVE-2026-68166userfaultfd: prevent registration of special VMAs
- —Not scoredno CVSS score yet
- 0.21%Exploitation in 30 daysEPSS · top 89% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
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.
Timeline
ID reserved
By Linux
- 11 days later
· 11 days later
Published
- 3 months later
· 3 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
No CVSS score yet: neither the CNA, CISA nor NVD has scored this CVE. NVD status: Received.
- EPSS (exploitation in 30 days)
- 0.21% · top 89% of all CVEs (12 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Not scored.
Affected products
- affected 54007f818206dc27309ca423df4c87dd160a7208 – < d974b4b786214883bd8e56bda10b454c80fd6205
- affected 54007f818206dc27309ca423df4c87dd160a7208 – < 495a28d5a100be1b232633f4c2dcc42ba10b3796
- affected 54007f818206dc27309ca423df4c87dd160a7208 – < 165613191ad9d034bf17c00e3a142f9561597ec5
- affected 54007f818206dc27309ca423df4c87dd160a7208 – < 0c26202b157f1efc3cd2f26f5c30f59b508a6a5d
- affected 54007f818206dc27309ca423df4c87dd160a7208 – < 3c58f641e813c3c71039f8fd4d4e2a3aab713288
- affected 6.6
- unaffected < 6.6
- unaffected 6.6.153 – ≤ 6.6.*
- unaffected 6.12.105 – ≤ 6.12.*
- unaffected 6.18.44 – ≤ 6.18.*
- unaffected 7.1.6 – ≤ 7.1.*
- unaffected 7.2 – ≤ *
References
References5
- https://git.kernel.org/stable/c/d974b4b786214883bd8e56bda10b454c80fd6205 (opens in a new tab)
- https://git.kernel.org/stable/c/495a28d5a100be1b232633f4c2dcc42ba10b3796 (opens in a new tab)
- https://git.kernel.org/stable/c/165613191ad9d034bf17c00e3a142f9561597ec5 (opens in a new tab)
- https://git.kernel.org/stable/c/0c26202b157f1efc3cd2f26f5c30f59b508a6a5d (opens in a new tab)
- https://git.kernel.org/stable/c/3c58f641e813c3c71039f8fd4d4e2a3aab713288 (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-55552 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-68166)Record last updated .