---
id: "CVE-2026-122192"
kind: "vulnerability"
aliases: ["CVE-2026-122192"]
title: "Improper handling of a failed memory remap in Firecracker versions 0.23.0 through 1.16.1 might allow a guest user\u2026"
severity: "high"
cvss: 7.5
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["aws", "firecracker", "infrastructure", "lab-disclosure", "microvm", "self-hosted"]
not_affected_if: ["managed-hosting", "no-balloon-or-virtio-mem", "no-snapshot-restore", "uffd-backend"]
published_at: "2026-11-04T20:19:12+00:00"
first_seen_at: "2026-11-04T19:56:47+00:00"
updated_at: "2026-11-04T20:40:33+00:00"
sources: [{"source": "lab", "url": "https://aws.amazon.com/security/security-bulletins/rss/2026-169-aws/", "first_seen_at": "2026-11-04T19:56:47+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-122192", "first_seen_at": "2026-11-04T20:29:03+00:00"}]
---

# Improper handling of a failed memory remap in Firecracker versions 0.23.0 through 1.16.1 might allow a guest user…

Firecracker is an open source virtualization technology used by AWS Lambda. Under certain host memory conditions, a root user inside a guest VM restored from a snapshot can read or modify memory of the Firecracker process.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the Firecracker version with `firecracker --version`; affected versions are `v0.23.0` through `v1.16.1`.
- Check whether VMs are restored from snapshots using the File memory backend together with a balloon or virtio-mem device.
- Check host overcommit with `sysctl vm.overcommit_memory` and the kernel version with `uname -r`.

## Fix

- Firecracker `v1.16.2` or `v1.17.0` (or later).
- Operators maintaining forks or derivative code should incorporate the corresponding fixes.

## Timeline

- 2026-11-04T19:56:47+00:00 lab https://aws.amazon.com/security/security-bulletins/rss/2026-169-aws/ — AWS: CVE-2026-122192: Guest Access to Firecracker Process Memory After a Failed Memory Discard
- 2026-11-04T20:29:03+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-122192

## Documents

- [advisory] AWS: CVE-2026-122192: Guest Access to Firecracker Process Memory After a Failed Memory Discard https://aws.amazon.com/security/security-bulletins/rss/2026-169-aws/
- [advisory] Vendor advisory: github.com https://github.com/firecracker-microvm/firecracker/security/advisories/GHSA-48ww-rqpp-2mgm
- [fix] Release notes: github.com https://github.com/firecracker-microvm/firecracker/releases/tag/v1.16.2
- [fix] Release notes: github.com https://github.com/firecracker-microvm/firecracker/releases/tag/v1.17.0

## From the sources

CVE-2026-122192: Guest Access to Firecracker Process Memory After a Failed Memory Discard

### CVE-2026-122192: Guest Access to Firecracker Process Memory After a Failed Memory Discard

Bulletin ID: 2026-169-AWS Scope: AWS Content Type: Important (requires attention) Publication Date: 11/04/2026 11:30 AM PST

Description:

Firecracker is an open source virtualization technology that powers AWS Lambda and other serverless compute services. We identified CVE-2026-122192, an issue in Firecracker v0.23.0 through v1.16.1 that, under certain host memory conditions, can let a root user in a guest read or modify memory of the Firecracker process. It affects VMs restored from a snapshot using the File memory backend with a balloon or virtio-mem device.

AWS services including AWS Lambda are not affected by this issue. No customer action is required.

Impacted versions: Firecracker v0.23.0 through v1.16.1, inclusive.

Within the currently supported release lines, v1.16.0 and v1.16.1 are affected. The fix is included in v1.16.2 and v1.17.0

Resolution:

This issue is fixed in Firecracker v1.16.2 and v1.17.0. If you restore VMs using the File memory backend with a balloon or virtio-mem device, we recommend upgrading to Firecracker v1.16.2, v1.17.0 or later. Operators maintaining forks or derivative code should incorporate the corresponding fixes.

Workarounds:

If upgrading is not immediately possible, restore snapshots using the Uffd memory backend, following its documented requirements for handling discarded pages.

The following measures address known host-memory failure conditions:

- On kernels without the Linux 6.12 overcommit-handling change, use heuristic overcommit (vm.overcommit_memory=0) and keep the maximum discard size no greater than the host’s total RAM plus swap.
- Keep the memory cgroup’s out-of-memory (OOM) killer enabled.

These measures do not prevent every replacement-mapping failure.

References:

- CVE-2026-122192
- GHSA-48ww-rqpp-2mgm

Acknowledgement:

We thank Juan Pablo Martinez Kuhn from Coinspect for collaborating on this issue through the coordinated vulnerability disclosure process.

 Please email aws-security@amazon.com with any security questions or concerns.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_