CVE-2026-90036: NFSD: Prevent client use-after-free during blocked-lock reaping
- Is it exploited?
Not on CISA's list. CISA has not added it to the Known Exploited Vulnerabilities catalog as of . If CISA adds it, this page shows it as known exploited.
- How likely is exploitation in the next 30 days?
- 0.5%
EPSS score, percentile 41.7 of all scored records. A probability estimated by FIRST, not a report of exploitation.
- How severe?
- 9.8 Critical
CVSS v3.1 base score, given by the CNA
- What should I do?
CISA has set no required action, because the vulnerability is not in KEV.
The CVE record links no vendor advisory, patch or mitigation.
- Which versions are affected?
Affected
- 4.9
Unaffected before 4.9; 6.6.160; 6.12.111; 6.18.51; 7.2.5; 7.3
Source: CISA KEV 2026.10.29, as of ; FIRST EPSS, as of ; CVE List, as of . About the data.
What to do
Advisories and patches
The CVE record links no vendor advisory, patch or mitigation.
This summary is based on the CVE record as of . Check the vendor's advisory before you act: affected versions and fixes can change.
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Affected | from 7919d0a27f1e to before 0d53a47c913d |
| Affected | from 7919d0a27f1e to before 7081224a59a0 |
| Affected | from 7919d0a27f1e to before cd489b035873 |
| Affected | from 7919d0a27f1e to before 6fedb2eaff77 |
| Affected | from 7919d0a27f1e to before 9026932ac8be |
Versions not listed are: unaffected.
| Status | Versions |
|---|---|
| Affected | 4.9 |
| Unaffected | before 4.9 |
| Unaffected | 6.6.160 |
| Unaffected | 6.12.111 |
| Unaffected | 6.18.51 |
| Unaffected | 7.2.5 |
| Unaffected | 7.3 |
Versions not listed are: affected.
Versions the record lists as unaffected: 6.6.160, 6.12.111, 6.18.51, 7.2.5, 7.3.
Source: CVE List, as of . About the data.
About this vulnerability
In the Linux kernel, the following vulnerability has been resolved: NFSD: Prevent client use-after-free during blocked-lock reaping A bare lock owner -- its only remaining reference a blocked lock on nn->blocked_locks_lru -- holds a raw pointer to its nfs4_client but no reference keeping the client alive. When the per-net laundromat reaps such a lock, freeing the nbl drops the owner reference h…
Summary: CVE record, as of .
- CISA has not added CVE-2026-90036 to its Known Exploited Vulnerabilities (KEV) catalog, as of 29 Oct 2026.
- The CVE record was published on 16 Sep 2026.
- The CVE record carries a CVSS v3.1 base score of 9.8 (Critical), given by its CNA.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 0.5% (percentile 41.7), as of 29 Oct 2026. EPSS is a statistical estimate, not a report of exploitation.
Source: CISA KEV 2026.10.29, as of ; CVE List, as of ; FIRST EPSS, as of . About the data.
Description
NFSD: Prevent client use-after-free during blocked-lock reaping
In the Linux kernel, the following vulnerability has been resolved: NFSD: Prevent client use-after-free during blocked-lock reaping A bare lock owner -- its only remaining reference a blocked lock on nn->blocked_locks_lru -- holds a raw pointer to its nfs4_client but no reference keeping the client alive. When the per-net laundromat reaps such a lock, freeing the nbl drops the owner reference held through flc_owner, and the final nfs4_put_stateowner() takes the client's cl_lock. Because the laundromat detaches the nbl first, __destroy_client() no longer finds it, so a concurrent force_expire_client() can free the client before nfs4_put_stateowner() runs, dereferencing cl_lock in freed memory. Pin the client with cl_rpc_users before dropping nn->blocked_locks_lock, and skip clients already expiring, whose blocked locks __destroy_client() frees while holding an owner reference. Take nn->client_lock outside nn->blocked_locks_lock. Every other site holds nn->blocked_locks_lock as a leaf, acquiring no further lock, so placing nn->client_lock outside it cannot form a lock-order cycle.
Source: CVE List, as of . About the data.
Timeline
| Date | Event |
|---|---|
| CVE record published | |
| CVE record last updated |
Known exploited Linux vulnerabilities
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- CVE-2026-53362: Linux Kernel Unspecified Vulnerability