What is CVE-2026-90036?

CVE-2026-90036 is a Critical severity Linux kernel vulnerability with a CVSS score of 9.8 out of 10, affecting Linux kernel versions from 4.9 onward and patched in 6.12.111, 6.18.51, 7.2.5 and others. CVE-2026-90036 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2026-90036?

CVE-2026-90036 has a CVSS score of 9.8 out of 10, rated Critical severity. The vector string is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Is there a patch available for CVE-2026-90036?

Yes, CVE-2026-90036 has been patched. Fixed versions include 6.12.111, 6.18.51, 7.2.5 and others. If you are running Linux kernel 4.9 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2026-90036 actively exploited?

CVE-2026-90036 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2026-90036

Critical

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.

Package Linux Kernel

Published 2026-09-16

Last modified 2026-09-21

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

9.8

out of 10

Critical

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Vector string

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

Affected versions

Linux kernel versions 4.9 and later are affected. Fixed in 6.12.111, 6.18.51, 7.2.5, 7.3-rc1 and their respective stable series.

Affected from

≥ 4.9

Fixed in

✓ 6.12.111 6.12.x ✓ 6.18.51 6.18.x ✓ 7.2.5 7.2.x ✓ 7.3-rc1

References

4 total

Details

CVE ID CVE-2026-90036

Severity Critical

CVSS score 9.8 / 10

CVSS version 3.1

Published 2026-09-16

Modified 2026-09-21

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2026-90036?

CVE-2026-90036 is a Critical severity Linux kernel vulnerability with a CVSS score of 9.8 out of 10 . It affects Linux kernel versions from 4.9 onward and has been patched in 6.12.111, 6.18.51, 7.2.5 and others. CVE-2026-90036 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2026-90036?

CVE-2026-90036 has a CVSS score of 9.8 out of 10, rated Critical severity (CVSS 3.1). The vector string is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
Is there a patch available for CVE-2026-90036?

Yes. CVE-2026-90036 has been patched. Fixed versions include 6.12.111, 6.18.51, 7.2.5 and others. If you are running Linux kernel 4.9 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2026-90036 actively exploited?

No. CVE-2026-90036 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.