Linux Kernel up to 63b91c8ff4589f5263873b24c052447a28e10ef7 nfsd nfsd4_delegreturn initialization

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CTI Interest Score
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6.2$0-$5k0.00

Summaryinfo

A vulnerability was found in Linux Kernel. It has been rated as critical. The impacted element is the function nfsd4_delegreturn of the component nfsd. This manipulation causes initialization. This vulnerability is handled as CVE-2025-37871. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability classified as critical was found in Linux Kernel. Affected by this vulnerability is the function nfsd4_delegreturn of the component nfsd. The manipulation with an unknown input leads to a initialization vulnerability. The CWE definition for the vulnerability is CWE-665. The product does not initialize or incorrectly initializes a resource, which might leave the resource in an unexpected state when it is accessed or used. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: nfsd: decrease sc_count directly if fail to queue dl_recall A deadlock warning occurred when invoking nfs4_put_stid following a failed dl_recall queue operation: T1 T2 nfs4_laundromat nfs4_get_client_reaplist nfs4_anylock_blockers __break_lease spin_lock // ctx->flc_lock spin_lock // clp->cl_lock nfs4_lockowner_has_blockers locks_owner_has_blockers spin_lock // flctx->flc_lock nfsd_break_deleg_cb nfsd_break_one_deleg nfs4_put_stid refcount_dec_and_lock spin_lock // clp->cl_lock When a file is opened, an nfs4_delegation is allocated with sc_count initialized to 1, and the file_lease holds a reference to the delegation. The file_lease is then associated with the file through kernel_setlease. The disassociation is performed in nfsd4_delegreturn via the following call chain: nfsd4_delegreturn --> destroy_delegation --> destroy_unhashed_deleg --> nfs4_unlock_deleg_lease --> kernel_setlease --> generic_delete_lease The corresponding sc_count reference will be released after this disassociation. Since nfsd_break_one_deleg executes while holding the flc_lock, the disassociation process becomes blocked when attempting to acquire flc_lock in generic_delete_lease. This means: 1) sc_count in nfsd_break_one_deleg will not be decremented to 0; 2) The nfs4_put_stid called by nfsd_break_one_deleg will not attempt to acquire cl_lock; 3) Consequently, no deadlock condition is created. Given that sc_count in nfsd_break_one_deleg remains non-zero, we can safely perform refcount_dec on sc_count directly. This approach effectively avoids triggering deadlock warnings.

The advisory is shared at git.kernel.org. This vulnerability is known as CVE-2025-37871 since 04/16/2025. The exploitation appears to be difficult. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 01/31/2026).

The vulnerability scanner Nessus provides a plugin with the ID 237255 (Debian dla-4178 : ata-modules-5.10.0-34-armmp-di - security update), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.10.237, 5.15.181, 6.1.135, 6.6.88, 6.12.25, 6.14.4, 6.15-rc1 or 6.15-rc3 eliminates this vulnerability. Applying the patch b9bbe8f9d5663311d06667ce36d6ed255ead1a26/a70832d3555987035fc430ccd703acd89393eadb/ba903539fff745d592d893c71b30e5e268a95413/7d192e27a431026c58d60edf66dc6cd98d0c01fc/a7fce086f6ca84db409b9d58493ea77c1978897c/14985d66b9b99c12995dd99d1c6c8dec4114c2a5/a1d14d931bf700c1025db8c46d6731aa5cf440f9 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (237255) and CERT Bund (WID-SEC-2025-0991). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Affected

  • Debian Linux
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • Dell Avamar
  • Open Source Linux Kernel
  • Dell NetWorker
  • Dell Secure Connect Gateway

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.3
VulDB Meta Temp Score: 6.2

VulDB Base Score: 7.1
VulDB Temp Score: 6.8
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 5.5
NVD Vector: 🔍

CVSSv2info

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

Exploitinginfo

Class: Initialization
CWE: CWE-665
CAPEC: 🔍
ATT&CK: 🔍

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Nessus ID: 237255
Nessus Name: Debian dla-4178 : ata-modules-5.10.0-34-armmp-di - security update

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Upgrade: Kernel 5.10.237/5.15.181/6.1.135/6.6.88/6.12.25/6.14.4/6.15-rc1/6.15-rc3
Patch: b9bbe8f9d5663311d06667ce36d6ed255ead1a26/a70832d3555987035fc430ccd703acd89393eadb/ba903539fff745d592d893c71b30e5e268a95413/7d192e27a431026c58d60edf66dc6cd98d0c01fc/a7fce086f6ca84db409b9d58493ea77c1978897c/14985d66b9b99c12995dd99d1c6c8dec4114c2a5/a1d14d931bf700c1025db8c46d6731aa5cf440f9

Timelineinfo

04/16/2025 🔍
05/09/2025 +23 days 🔍
05/09/2025 +0 days 🔍
01/31/2026 +267 days 🔍

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2025-37871 (🔍)
GCVE (CVE): GCVE-0-2025-37871
GCVE (VulDB): GCVE-100-308161
CERT Bund: WID-SEC-2025-0991 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 05/09/2025 09:10
Updated: 01/31/2026 02:25
Changes: 05/09/2025 09:10 (58), 05/09/2025 15:24 (1), 05/27/2025 06:05 (2), 11/13/2025 02:07 (11), 01/31/2026 02:25 (7)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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