CRITICAL: CVE-2026-53399 (CVSS 9.8) — multiple products

CVE: CVE-2026-53399

CVSS: 9.8 (3.1) — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Severity: CRITICAL

Status: Critical advisory

Affected

_See vendor advisory_

Summary

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).

Verified Sources

• NVD entry
• GitHub Advisory
• MITRE

References

• https://git.kernel.org/stable/c/30d55c8aabb261bc3f427d6b9aae7ef6206063f9
• https://git.kernel.org/stable/c/83c2b7797742339bb768f83935f7ca33950db138
• https://git.kernel.org/stable/c/8dee7c278f1c2b5bb80e17a6281c3812fc8b0cdd
• https://git.kernel.org/stable/c/d369e5edfaaf83a448016e2f1da392b2174be801

_Validated by the Lyrie Threat Intelligence Pipeline — 3 independent sources confirmed before publication. No speculation._