CVE-2026-89715 - Vulnerability Details

- NFS/localio: fix ref leak on nfs_uuid_add_file failure

Description

In the Linux kernel, the following vulnerability has been resolved:

NFS/localio: fix ref leak on nfs_uuid_add_file failure

When nfs_uuid_add_file() races with nfs_uuid_put() tearing down
uuid->net, it returns -ENXIO without publishing nfl->nfs_uuid via
rcu_assign_pointer(). nfs_open_local_fh() then enters its error
branch and only releases the slot's file ref and its paired net
ref plus its own entry-time net ref, while the close path is a
no-op:

nfs_close_local_fh()
nfs_uuid = rcu_dereference(nfl->nfs_uuid);
if (!nfs_uuid) { rcu_read_unlock(); return; } /* always */

nfsd_open_local_fh() returns localio holding a caller-owned +1
nfsd_file reference (from nfsd_file_get() after
nfsd_file_acquire_local()) and an entry-time nfsd_net reference
(from its first nfsd_net_try_get()) embedded as nf->nf_net. Both
are leaked on the failure path, pinning one nfsd_file (and the
underlying struct file, dentry, inode) and one nfsd_net_ref per
occurrence, which blocks nfsd_net and netns teardown.

Fix by releasing the caller-owned file ref and its net ref through
the existing helper, using a stack-local RCU pointer so the helper
can xchg it out, then returning -ENXIO so callers do not
dereference a localio whose slot has been cleared:

struct nfsd_file __rcu *tmp = RCU_INITIALIZER(localio);

nfs_to_nfsd_file_put_local(pnf);
nfs_to_nfsd_file_put_local(&tmp);
localio = ERR_PTR(-ENXIO);

The trailing nfs_to_nfsd_net_put(net) continues to release the
outer net ref, so all three nfsd_net_try_get() increments are
balanced on the error branch.

Published: 2026-09-11

Score: 5.3 Medium

EPSS: < 1% Very Low

KEV: No

Impact:

Action:

Analysis

Impact

A race condition between nfs_uuid_add_file() and nfs_uuid_put() in the Linux kernel NFS local‑I/O subsystem can leak reference counts for nfsd_file objects and network namespace references. The leaked references prevent proper teardown of the NFS daemon and its namespace, causing kernel resource exhaustion and a denial of service for the NFS service.

Affected Systems

The flaw affects the Linux kernel, specifically the NFS local‑I/O implementation. Any kernel that contains the vulnerable code path may be impacted. Administrators should verify whether their running kernel includes the nfs_uuid_add_file() logic and apply updates accordingly.

Risk and Exploitability

The CVSS score of 5.3 indicates moderate severity, and the EPSS score of less than 1% suggests a low likelihood of public exploitation. The vulnerability is not listed in the CISA KEV catalog. Based on the description, it is inferred that exploitation would require local interaction with the kernel, typically through privileged processes or repeated NFS operations that trigger the race. An attacker could repeatedly cause failures to accumulate leaked references, eventually exhausting kernel resources and causing the NFS daemon to fail.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Linux

unaffected

Version	Status	Constraints
`fdd015de767977f21892329af5e12276eb80375f`	affected	< 5215e734bf7cba18237155f8cb2a0accb60ca339
`fdd015de767977f21892329af5e12276eb80375f`	affected	< 9f59b05423ed381f8cdeaaae4bd6778adcb6865c
`fdd015de767977f21892329af5e12276eb80375f`	affected	< ca018c19e0ba38975e5ddc3ef8117d5b734313aa
`55735dc5a0ee0c0fc14cb51e005eae862906a410`	affected	—
`7cac8a129fc53497f9ee5d66fca55a245d009b97`	affected	—
`6.15.10`	affected	< 6.16
`6.16.1`	affected	< 6.17

Linux

affected

Version	Status	Constraints
`6.17`	affected	—
`0`	unaffected	< 6.17
`6.18.50`	unaffected	≤ 6.18.*
`7.2.4`	unaffected	≤ 7.2.*
`7.3-rc1`	unaffected	≤ *

No data.

Vendor Product Confidence Versions

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`[fdd015de767977f21892329af5e12276eb80375f,5215e734bf7cba18237155f8cb2a0accb60ca339)`	affected	code_commit	—
`[fdd015de767977f21892329af5e12276eb80375f,9f59b05423ed381f8cdeaaae4bd6778adcb6865c)`	affected	code_commit	—
`[fdd015de767977f21892329af5e12276eb80375f,ca018c19e0ba38975e5ddc3ef8117d5b734313aa)`	affected	code_commit	—
`55735dc5a0ee0c0fc14cb51e005eae862906a410`	affected	code_commit	—
`7cac8a129fc53497f9ee5d66fca55a245d009b97`	affected	code_commit	—
`[6.15.10,6.16)`	affected	semver	—
`[6.16.1,6.17)`	affected	semver	—

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`6.17`	affected	generic	—
`[0,6.17)`	unaffected	generic	—
`[6.18.50,6.19.0)`	unaffected	semver	—
`[7.2.4,7.3.0)`	unaffected	semver	—
`[7.3-rc1,*]`	unaffected	generic	—

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Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

Apply the latest kernel update that incorporates the nfs_uuid_add_file reference‑release fix.
If an update cannot be applied immediately, temporarily disable NFS local‑I/O or limit client access to reduce the window for the race condition.
Continuously monitor kernel logs for reference‑leak indications and restart the NFS daemon when resource exhaustion or repeated failures are detected.

Generated by OpenCVE AI on September 15, 2026 at 19:27 UTC.

Tracking

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Advisories

No advisories yet.

No CVSS v4.0

Attack Vector Network

Attack Complexity High

Privileges Required Low

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00206.

Key SSVC decision points have not yet been added.

References

Link	Providers
https://git.kernel.org/stable/c/5215e734bf7cba18237155f8cb2a0accb60ca339
https://git.kernel.org/stable/c/9f59b05423ed381f8cdeaaae4bd6778adcb6865c
https://git.kernel.org/stable/c/ca018c19e0ba38975e5ddc3ef8117d5b734313aa
https://nvd.nist.gov/vuln/detail/CVE-2026-89715
https://www.cve.org/CVERecord?id=CVE-2026-89715

History

Sat, 12 Sep 2026 14:45:00 +0000

Type	Values Removed	Values Added
Weaknesses	CWE-401

Sat, 12 Sep 2026 12:15:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-911
References		https://nvd.nist.gov/vuln/detail/CVE-2026-89715 https://www.cve.org/CVERecord?id=CVE-2026-89715
Metrics	threat_severity `None`	cvssV3_1 `{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H'}` threat_severity `Moderate`

Sat, 12 Sep 2026 08:30:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-401

Fri, 11 Sep 2026 23:45:00 +0000

Type	Values Removed	Values Added
Description		In the Linux kernel, the following vulnerability has been resolved: NFS/localio: fix ref leak on nfs_uuid_add_file failure When nfs_uuid_add_file() races with nfs_uuid_put() tearing down uuid->net, it returns -ENXIO without publishing nfl->nfs_uuid via rcu_assign_pointer(). nfs_open_local_fh() then enters its error branch and only releases the slot's file ref and its paired net ref plus its own entry-time net ref, while the close path is a no-op: nfs_close_local_fh() nfs_uuid = rcu_dereference(nfl->nfs_uuid); if (!nfs_uuid) { rcu_read_unlock(); return; } /* always / nfsd_open_local_fh() returns localio holding a caller-owned +1 nfsd_file reference (from nfsd_file_get() after nfsd_file_acquire_local()) and an entry-time nfsd_net reference (from its first nfsd_net_try_get()) embedded as nf->nf_net. Both are leaked on the failure path, pinning one nfsd_file (and the underlying struct file, dentry, inode) and one nfsd_net_ref per occurrence, which blocks nfsd_net and netns teardown. Fix by releasing the caller-owned file ref and its net ref through the existing helper, using a stack-local RCU pointer so the helper can xchg it out, then returning -ENXIO so callers do not dereference a localio whose slot has been cleared: struct nfsd_file __rcu tmp = RCU_INITIALIZER(localio); nfs_to_nfsd_file_put_local(pnf); nfs_to_nfsd_file_put_local(&tmp); localio = ERR_PTR(-ENXIO); The trailing nfs_to_nfsd_net_put(net) continues to release the outer net ref, so all three nfsd_net_try_get() increments are balanced on the error branch.
Title		NFS/localio: fix ref leak on nfs_uuid_add_file failure
First Time appeared		Linux Linux linux Kernel
CPEs		cpe:2.3:o:linux:linux_kernel::::::::
Vendors & Products		Linux Linux linux Kernel
References		https://git.kernel.org/stable/c/5215e734bf7cba18237155f8cb2a0accb60ca339 https://git.kernel.org/stable/c/9f59b05423ed381f8cdeaaae4bd6778adcb6865c https://git.kernel.org/stable/c/ca018c19e0ba38975e5ddc3ef8117d5b734313aa

Subscriptions

Linux Linux Kernel

MITRE

Status: PUBLISHED

Assigner: Linux

Published: 2026-09-11T19:46:29.227Z

Updated: 2026-09-11T19:46:29.227Z

Reserved: 2026-09-11T19:38:34.751Z

Link: CVE-2026-89715

Vulnrichment

No data.

NVD

Status : Received

Published: 2026-09-11T20:19:58.993

Modified: 2026-09-11T20:19:58.993

Link: CVE-2026-89715

Redhat

Severity : Moderate

Publid Date: 2026-09-11T19:46:29Z

Links: CVE-2026-89715 - Bugzilla

OpenCVE Enrichment

Updated: 2026-09-15T19:30:12Z

Weaknesses

CWE-911
Improper Update of Reference Count

Impact

Affected Systems

Risk and Exploitability

Tracking

Attack Vector Network

Attack Complexity High

Privileges Required Low

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

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