What is CVE-2026-89659?

CVE-2026-89659 is a Critical severity Linux kernel vulnerability with a CVSS score of 9.8 out of 10, affecting Linux kernel versions from 3.10 onward and patched in 6.12.111, 6.18.51, 7.2.4 and others. CVE-2026-89659 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2026-89659?

CVE-2026-89659 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-2026-89659?

Yes, CVE-2026-89659 has been patched. Fixed versions include 6.12.111, 6.18.51, 7.2.4 and others. If you are running Linux kernel 3.10 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2026-89659 actively exploited?

CVE-2026-89659 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2026-89659

Critical

In the Linux kernel, the following vulnerability has been resolved: NFSD: Prevent client use-after-free during delegation revoke A delegation stateid holds only a bare pointer to its owning nfs4_client and does not keep it alive. The client survives its stateids only because __destroy_client() drains cl_delegations and cl_revoked before free_client() runs. nfs4_laundromat() breaks that invariant: it unhashes an expired delegation from cl_delegations, drops deleg_lock, then revoke_delegation() relinks it onto cl_revoked under cl_lock. In that window the delegation is on neither list, so client_has_state() can report no remaining state. Every teardown path first requires cl_rpc_users to be zero, but the laundromat holds no such reference. A client whose recalled delegation has just timed out can therefore reach free_client() while revoke_delegation() is still about to dereference cl_lock, a use-after-free. Pin the client with cl_rpc_users across the revoke so teardown blocks until it completes, then reap the delegation from cl_revoked. A client already expiring reaps its own, so skip it and leave the delegation on del_recall_lru.

Package Linux Kernel

Published 2026-09-11

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 3.10 and later are affected. Fixed in 6.12.111, 6.18.51, 7.2.4, 7.3-rc1 and their respective stable series.

Affected from

≥ 3.10

Fixed in

✓ 6.12.111 6.12.x ✓ 6.18.51 6.18.x ✓ 7.2.4 7.2.x ✓ 7.3-rc1

References

4 total

Details

CVE ID CVE-2026-89659

Severity Critical

CVSS score 9.8 / 10

CVSS version 3.1

Published 2026-09-11

Modified 2026-09-21

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2026-89659?

CVE-2026-89659 is a Critical severity Linux kernel vulnerability with a CVSS score of 9.8 out of 10 . It affects Linux kernel versions from 3.10 onward and has been patched in 6.12.111, 6.18.51, 7.2.4 and others. CVE-2026-89659 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2026-89659?

CVE-2026-89659 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-2026-89659?

Yes. CVE-2026-89659 has been patched. Fixed versions include 6.12.111, 6.18.51, 7.2.4 and others. If you are running Linux kernel 3.10 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2026-89659 actively exploited?

No. CVE-2026-89659 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.