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CVE-2026-22980· NVD / CVE Program· CNA Linux

nfsd: provide locking for v4_end_grace

In the Linux kernel, the following vulnerability has been resolved: nfsd: provide locking for v4_end_grace Writing to v4_end_grace can race with server shutdown and result in memory being accessed after it was freed - reclaim_str_hashtbl in particularly. We cannot hold nfsd_mutex across the nfsd4_end_grace() call as that is held while client_tracking_op->init() is called and that can wait for an upcall to nfsdcltrack which can write to v4_end_grace, resulting in a deadlock. nfsd4_end_grace() is also called by the landromat work queue and this doesn't require locking as server shutdown will stop the work and wait for it before freeing anything that nfsd4_end_grace() might access. However, we must be sure that writing to v4_end_grace doesn't restart the work item after shutdown has already waited for it. For this we add a new flag protected with nn->client_lock. It is set only while it is safe to make client tracking calls, and v4_end_grace only schedules work while the flag is set with the spinlock held. So this patch adds a nfsd_net field "client_tracking_active" which is set as described. Another field "grace_end_forced", is set when v4_end_grace is written. After this is set, and providing client_tracking_active is set, the laundromat is scheduled. This "grace_end_forced" field bypasses other checks for whether the grace period has finished. This resolves a race which can result in use-after-free.

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
Jan 23, 2026
Updated
Sep 8, 2026
EPSS
0.1% · 3th percentile
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Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
7.8
CNA · Linux
7.8
agree

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Affected systems

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel3.18 and later · before 5.10.248
  • linux linux kernel5.11 and later · before 5.15.198
  • linux linux kernel5.16 and later · before 6.1.161
  • linux linux kernel6.2 and later · before 6.6.121
  • linux linux kernel6.7 and later · before 6.12.66
  • linux linux kernel6.13 and later · before 6.18.6
  • linux linux kernel6.19

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 3.18affected
    • 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 and later · before ca97360860eb02e3ae4ba42c19b439a0fcecbf06affected · git
    • 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 and later · before e8bfa2401d4c51eca6e48e9b33c798828ca9df61affected · git
    • 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 and later · before 34eb22836e0cdba093baac66599d68c4cd245a9daffected · git
    • 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 and later · before 06600719d0f7a723811c45e4d51f5b742f345309affected · git
    • 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 and later · before ba4811c8b433bfa681729ca42cc62b6034f223b0affected · git
    • 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 and later · before 53f07d095e7e680c5e4569a55a019f2c0348cdc6affected · git
    • 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 and later · before 2857bd59feb63fcf40fe4baf55401baea6b4feb4affected · git
    • before 3.18not affected · semver
    • 5.10.248 and later · up to and including 5.10.*not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.162-16.1.162-1
Debian:13linuxbefore 6.12.69-16.12.69-1
Debian:14linuxbefore 6.18.8-16.18.8-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

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    85Now
  • CVE-2016-5195Race condition in mm/gup.c in the Linux kernel 2.x through 4.x before 4.8.3 allows local users to gain privileges by leveraging incorrect haKEV
    83Now
  • CVE-2019-13272In the Linux kernel before 5.1.17, ptrace_link in kernel/ptrace.c mishandles the recording of the credentials of a process that wants to creKEV
    77This week
  • CVE-2013-6282The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the v6k and v7 ARM platforms do not validate certain addKEV
    77This week
  • CVE-2013-2094The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9 uses an incorrect integer data type, which allows loKEV
    77This week

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux06600719d0f7a723811c45e4d51f5b742f345309Vendor (CNA)
Linux Linux2857bd59feb63fcf40fe4baf55401baea6b4feb4Vendor (CNA)
Linux Linux34eb22836e0cdba093baac66599d68c4cd245a9dVendor (CNA)
Linux Linux53f07d095e7e680c5e4569a55a019f2c0348cdc6Vendor (CNA)
Linux Linuxba4811c8b433bfa681729ca42cc62b6034f223b0Vendor (CNA)
Linux Linuxca97360860eb02e3ae4ba42c19b439a0fcecbf06Vendor (CNA)
Linux Linuxe8bfa2401d4c51eca6e48e9b33c798828ca9df61Vendor (CNA)
cbl2 kernel 5.15.186.1-1 on CBL Mariner 2.05.15.200.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.1.162-1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-416 · Use After Free

CVSS vector

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

nvd-primary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

The bug in code

The whole CWE-416 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

c
free(dev->buf);/* ... another thread is still running ... */process(dev->buf);

Fixed

c
lock(&dev->lock);free(dev->buf);dev->buf = NULL;unlock(&dev->lock);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Noroxi analysis

No Noroxi analysis for this record yet

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Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records