# CVE-2026-68428: KVM: x86/mmu: Fix use-after-free on vendor module reload

Status: published. Published: 2026-08-10. Updated: 2026-11-06.

In the Linux kernel, the following vulnerability has been resolved:

KVM: x86/mmu: Fix use-after-free on vendor module reload

mmu_destroy_caches() destroys pte_list_desc_cache and
mmu_page_header_cache, but leaves both pointers unchanged.  The pointers
live in kvm.ko, and therefore survive when a vendor module is unloaded
while kvm.ko remains loaded.

If creation of pte_list_desc_cache fails during a subsequent vendor
module load, its assignment sets pte_list_desc_cache to NULL and the
error path calls mmu_destroy_caches().  mmu_page_header_cache still
points to the cache destroyed during the preceding vendor module
unload.  Passing that stale pointer to kmem_cache_destroy() causes a
slab use-after-free.

Reproduce the issue on a v7.1.3 kernel with CONFIG_KASAN=y,
CONFIG_KASAN_GENERIC=y, CONFIG_KVM=m, and CONFIG_KVM_INTEL=m.  A
one-shot test hook forces pte_list_desc_cache to NULL on the second
invocation of kvm_mmu_vendor_module_init():

  1. Load kvm.ko and kvm-intel.ko, creating both caches.
  2. Unload only kvm_intel, leaving kvm.ko loaded.
  3. Reload kvm_intel and force initialization through the -ENOMEM path.

KASAN reports:

  BUG: KASAN: slab-use-after-free in
  kvm_mmu_vendor_module_init+0x5b/0x170 [kvm]
  ...
  kmem_cache_destroy+0x21/0x1d0
  kvm_mmu_vendor_module_init+0x5b/0x170 [kvm]
  ...
  Allocated by task 16817:
  __kmem_cache_create_args+0x12c/0x3b0
  __kmem_cache_create.constprop.0+0xb6/0xf0 [kvm]
  kvm_mmu_vendor_module_init+0x13b/0x170 [kvm]
  ...
  Freed by task 16820:
  kmem_cache_destroy+0x117/0x1d0
  kvm_mmu_vendor_module_exit+0x21/0x30 [kvm]

Clear both pointers immediately after destroying their caches so that
the stored state reflects the caches' lifetime and repeated cleanup is
safe.

With the fix applied, the same injected vendor module reload fails with
-ENOMEM as expected and produces no KASAN report.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- Linux / Linux: ≥ cb498ea2ce1d3f3c0bc0a2522241dca10263e437; < 034b7fa1f5846d69eb51f12ce6d1c71871e83c2d (affected, git); ≥ cb498ea2ce1d3f3c0bc0a2522241dca10263e437; < 42272b0f239f3a89f9c26a01cc37aee06138b1b7 (affected, git); ≥ cb498ea2ce1d3f3c0bc0a2522241dca10263e437; < 940950d5cd86f250dca578279ad5ca63b4e0986b (affected, git); ≥ cb498ea2ce1d3f3c0bc0a2522241dca10263e437; < 6f4be73880302d5642c83a0813fdfe1f5fd4b6e3 (affected, git); ≥ cb498ea2ce1d3f3c0bc0a2522241dca10263e437; < 32b9f89ed9e6d7a45075d64089c254a7f6e13695 (affected, git); ≥ cb498ea2ce1d3f3c0bc0a2522241dca10263e437; < ec9daa8fd1b6f45545c9839dca55bd867fad9e13 (affected, git); ≥ cb498ea2ce1d3f3c0bc0a2522241dca10263e437; < 43cfb20d62ffe49626d62beecfc32eb6f262191c (affected, git); ≥ cb498ea2ce1d3f3c0bc0a2522241dca10263e437; < 52f2f7c30126037975389aa04d24c506a5177c35 (affected, git). Source: CNA: Linux
- Linux / Linux: 2.6.25 (affected); ≥ 0; < 2.6.25 (unaffected, semver); ≥ 5.10.265; ≤ 5.10.* (unaffected, semver); ≥ 5.15.216; ≤ 5.15.* (unaffected, semver); ≥ 6.1.183; ≤ 6.1.* (unaffected, semver); ≥ 6.6.148; ≤ 6.6.* (unaffected, semver); ≥ 6.12.101; ≤ 6.12.* (unaffected, semver); ≥ 6.18.42; ≤ 6.18.* (unaffected, semver); ≥ 7.1.6; ≤ 7.1.* (unaffected, semver); ≥ 7.2; ≤ * (unaffected, original_commit_for_fix). Source: CNA: Linux

## Severity and prioritization

- CISA KEV: No listing in collected sources

- EPSS: 0.17% as of 2026-11-06; percentile 5.72%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: Not reported

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://git.kernel.org/stable/c/034b7fa1f5846d69eb51f12ce6d1c71871e83c2d (CNA: Linux)

- https://git.kernel.org/stable/c/42272b0f239f3a89f9c26a01cc37aee06138b1b7 (CNA: Linux)

- https://git.kernel.org/stable/c/940950d5cd86f250dca578279ad5ca63b4e0986b (CNA: Linux)

- https://git.kernel.org/stable/c/6f4be73880302d5642c83a0813fdfe1f5fd4b6e3 (CNA: Linux)

- https://git.kernel.org/stable/c/32b9f89ed9e6d7a45075d64089c254a7f6e13695 (CNA: Linux)

- https://git.kernel.org/stable/c/ec9daa8fd1b6f45545c9839dca55bd867fad9e13 (CNA: Linux)

- https://git.kernel.org/stable/c/43cfb20d62ffe49626d62beecfc32eb6f262191c (CNA: Linux)

- https://git.kernel.org/stable/c/52f2f7c30126037975389aa04d24c506a5177c35 (CNA: Linux)

- https://git.kernel.org/stable/c/034b7fa1f5846d69eb51f12ce6d1c71871e83c2d (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/32b9f89ed9e6d7a45075d64089c254a7f6e13695 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/42272b0f239f3a89f9c26a01cc37aee06138b1b7 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/43cfb20d62ffe49626d62beecfc32eb6f262191c (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/52f2f7c30126037975389aa04d24c506a5177c35 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/6f4be73880302d5642c83a0813fdfe1f5fd4b6e3 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/940950d5cd86f250dca578279ad5ca63b4e0986b (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/ec9daa8fd1b6f45545c9839dca55bd867fad9e13 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

## Provenance

- CNA: Linux: https://www.cve.org/CVERecord?id=CVE-2026-68428; retrieved 2026-11-06; source updated 2026-11-06

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-68428; retrieved 2026-11-06; source updated 2026-11-06

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-68428; retrieved 2026-11-06; source updated Not reported

Revision: 5806b743913bc56b1810f4d80678179bb157bdb795be255af1463fcce8d08744

Canonical: https://y2.dev/cve/CVE-2026-68428

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

Collected public records only. Check source status for coverage and freshness.