# CVE-2026-46014: KVM: SVM: Add missing save/restore handling of LBR MSRs

> Missing save/restore handling of LBR MSRs in KVM SVM breaks virtualization state integrity, potentially allowing data corruption or leakage.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 27 May 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-88509, BELL-CVE-2026-46014, DEBIAN-CVE-2026-46014, GHSA-866w-999j-pr8g, ROOT-OS-DEBIAN-11-CVE-2026-46014, ROOT-OS-DEBIAN-12-CVE-2026-46014, ROOT-OS-DEBIAN-13-CVE-2026-46014, ROOT-OS-UBUNTU-2204-CVE-2026-46014, ROOT-OS-UBUNTU-2404-CVE-2026-46014, UBUNTU-CVE-2026-46014

## What is CVE-2026-46014?

CVE-2026-46014 is a medium-severity vulnerability in Linux kernel, published on 27 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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

KVM: SVM: Add missing save/restore handling of LBR MSRs

MSR_IA32_DEBUGCTLMSR and LBR MSRs are currently not enumerated by
KVM_GET_MSR_INDEX_LIST, and LBR MSRs cannot be set with KVM_SET_MSRS. So
save/restore is completely broken.

Fix it by adding the MSRs to msrs_to_save_base, and allowing writes to
LBR MSRs from userspace only (as they are read-only MSRs) if LBR
virtualization is enabled.  Additionally, to correctly restore L1's LBRs
while L2 is running, make sure the LBRs are copied from the captured
VMCB01 save area in svm_copy_vmrun_state().

Note, for VMX, this also fixes a flaw where MSR_IA32_DEBUGCTLMSR isn't
reported as an MSR to save/restore.

Note #2, over-reporting MSR_IA32_LASTxxx on Intel is ok, as KVM already
handles unsupported reads and writes thanks to commit b5e2fec0ebc3 ("KVM:
Ignore DEBUGCTL MSRs with no effect") (kvm_do_msr_access() will morph the
unsupported userspace write into a nop).

[sean: guard with lbrv checks, massage changelog]

Weakness: CWE-667 (Improper Locking)

## Which versions are affected by CVE-2026-46014?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-46014?

Apply the vendor's patch.

## Is CVE-2026-46014 being exploited?

There is no known exploitation of CVE-2026-46014 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-46014 and fix it if it is affected.

What it is: CVE-2026-46014 is a medium-severity vulnerability in Linux kernel, published on 27 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-46014 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-46014/ (Markdown: https://insights.sbomify.com/CVE-2026-46014/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-46014
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-46014
- OSV: https://osv.dev/vulnerability/CVE-2026-46014

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-46014/
Summaries are generated and may contain mistakes; the official description above is the record.