Linux Kernel up to 6.12.108/6.18.49/7.2.3 nfsd nfsd4_alloc_layout_stateid locking

CVSS Meta Temp Score
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CTI Interest Score
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6.2$0-$5k0.42+

Summaryinfo

A vulnerability, which was classified as critical, was found in Linux Kernel up to 6.12.108/6.18.49/7.2.3. This impacts the function nfsd4_alloc_layout_stateid of the component nfsd. Such manipulation leads to locking. This vulnerability is referenced as CVE-2026-89686. It is possible to launch the attack remotely. No exploit is available. You should upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Linux Kernel up to 6.12.108/6.18.49/7.2.3. Affected by this issue is the function nfsd4_alloc_layout_stateid of the component nfsd. The manipulation with an unknown input leads to a locking vulnerability. Using CWE to declare the problem leads to CWE-667. The product does not properly acquire or release a lock on a resource, leading to unexpected resource state changes and behaviors. Impacted is availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: nfsd: fix BUG_ON in nfsd4_alloc_layout_stateid on racing delegation revoke nfsd4_alloc_layout_stateid reads fp->fi_deleg_file without holding fi_lock when the parent stateid is a delegation. A concurrent delegation revoke via the laundromat can clear fi_deleg_file under fi_lock, causing nfsd_file_get() to return NULL and triggering the BUG_ON. This race is client-reachable: two NFS clients can trigger it by having one hold a delegation while another opens the same file to force a recall. When the first client doesn't respond to the recall, the laundromat revokes it. A concurrent LAYOUTGET from any client using the delegation stateid hits the race window. Fix this by taking fi_lock around the fi_deleg_file read in the SC_TYPE_DELEG path, matching the locking discipline of the find_any_file() arm, and replacing the BUG_ON with a graceful error return that cleans up the partially-initialized layout stateid.

The advisory is available at git.kernel.org. This vulnerability is handled as CVE-2026-89686 since 09/11/2026. The exploitation is known to be easy. The attack may be launched remotely. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 09/12/2026).

Upgrading to version 6.12.109, 6.18.50, 7.2.4 or 7.3-rc1 eliminates this vulnerability. Applying the patch c517f27498757e616d2a8fe6d16caad1fee422e6/607a56fea772c1f4f4989d8e255dd4f7192d9604/97bda8b4284d90897a1f1922e5082ff9e35d7c7e/ca94ba36172046be6a694a7986f6931e47ed4d51 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

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Version

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.5
VulDB Meta Temp Score: 6.2

VulDB Base Score: 6.5
VulDB Temp Score: 6.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Locking
CWE: CWE-667
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.12.109/6.18.50/7.2.4/7.3-rc1
Patch: c517f27498757e616d2a8fe6d16caad1fee422e6/607a56fea772c1f4f4989d8e255dd4f7192d9604/97bda8b4284d90897a1f1922e5082ff9e35d7c7e/ca94ba36172046be6a694a7986f6931e47ed4d51

Timelineinfo

09/11/2026 CVE reserved
09/12/2026 +1 days Advisory disclosed
09/12/2026 +0 days VulDB entry created
09/12/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-89686 (🔒)
GCVE (CVE): GCVE-0-2026-89686
GCVE (VulDB): GCVE-100-402950

Entryinfo

Created: 09/12/2026 02:06
Changes: 09/12/2026 02:06 (59)
Complete: 🔍
Cache ID: 216::103

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