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VulnerabilityPublished Updated

CVE-2026-53399: Linux kernel · nfsd: release layout stid on setlease failure

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 9.8 Critical · fixed in d788ef40a7517d22c97ab01700e4ae4c611b6f2f : patch Linux kernel as a priority.

Data as of 26 Oct 2026, 14:18 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.6% chance of exploitation in 30 days – higher than 51% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers can reliably automate steps 1–4 of the kill chain
Technical impact
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in d788ef40a7517d22c97ab01700e4ae4c611b6f2f, d369e5edfaaf83a448016e2f1da392b2174be801, 83c2b7797742339bb768f83935f7ca33950db138 +5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 19 Jul 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ c5c707f96fc9a6e5a57ca5baac892673270abe3d, < d788ef40a7517d22c97ab01700e4ae4c611b6f2f
Fixed in
  • d788ef40a7517d22c97ab01700e4ae4c611b6f2f
LinuxLinuxAffected
  • ≥ c5c707f96fc9a6e5a57ca5baac892673270abe3d, < d369e5edfaaf83a448016e2f1da392b2174be801
Fixed in
  • d369e5edfaaf83a448016e2f1da392b2174be801
LinuxLinuxAffected
  • ≥ c5c707f96fc9a6e5a57ca5baac892673270abe3d, < 83c2b7797742339bb768f83935f7ca33950db138
Fixed in
  • 83c2b7797742339bb768f83935f7ca33950db138
LinuxLinuxAffected
  • ≥ c5c707f96fc9a6e5a57ca5baac892673270abe3d, < 48a586e382e4db1dbf958d44b63e081df5f8ed04
Fixed in
  • 48a586e382e4db1dbf958d44b63e081df5f8ed04
LinuxLinuxAffected
  • ≥ c5c707f96fc9a6e5a57ca5baac892673270abe3d, < 30d55c8aabb261bc3f427d6b9aae7ef6206063f9
Fixed in
  • 30d55c8aabb261bc3f427d6b9aae7ef6206063f9
LinuxLinuxAffected
  • ≥ c5c707f96fc9a6e5a57ca5baac892673270abe3d, < 8dee7c278f1c2b5bb80e17a6281c3812fc8b0cdd
Fixed in
  • 8dee7c278f1c2b5bb80e17a6281c3812fc8b0cdd

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).

References

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