NVD / CVE Program· CNA Linux

CVE-2026-31403: NFSD: Hold net reference for the lifetime of /proc/fs/nfs/exports fd

Noroxi assessment

Priority: Monitor (action score 31/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.13% (FIRST EPSS).
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.
Fixed version: Linux Linux 6a8d70e2ad6aad2c345a5048edcb8168036f97d6, 76740c28050dc6db2f5550f1325b00a11bbb3255, c7f406fb341d6747634b8b1fa5461656e5e56076.

Low priority for now. Upgrade to Linux Linux 6a8d70e2ad6aad2c345a5048edcb8168036f97d6, 76740c28050dc6db2f5550f1325b00a11bbb3255, c7f406fb341d6747634b8b1fa5461656e5e56076 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: NFSD: Hold net reference for the lifetime of /proc/fs/nfs/exports fd The /proc/fs/nfs/exports proc entry is created at module init and persists for the module's lifetime. exports_proc_open() captures the caller's current network namespace and stores its svc_export_cache in seq->private, but takes no reference on the namespace. If the namespace is subsequently torn down (e.g. container destruction after the opener does setns() to a different namespace), nfsd_net_exit() calls nfsd_export_shutdown() which frees the cache. Subsequent reads on the still-open fd dereference the freed cache_detail, walking a freed hash table. Hold a reference on the struct net for the lifetime of the open file descriptor. This prevents nfsd_net_exit() from running -- and thus prevents nfsd_export_shutdown() from freeing the cache -- while any exports fd is open. cache_detail already stores its net pointer (cd->net, set by cache_create_net()), so exports_release() can retrieve it without additional per-file storage.

HighCVSS 7.8 · v3.1—No exploit Fix available

Memory safety

BDU:2026-05766

Published: Apr 3, 2026
Updated: Oct 19, 2026
EPSS: 0.1% · 2th percentile
CWE: CWE-416

Report tools

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Action score

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: —
CNA · Linux: 7.8; NVD has not scored this yet; the score shown is the CNA’s.

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

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Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
linux	linux kernel	cpe:2.3:o:linux:linux_kernel

Affected versions

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

linux linux kernel3.9 and later · before 5.10.253
linux linux kernel5.11 and later · before 6.1.167
linux linux kernel6.2 and later · before 6.6.130
linux linux kernel6.7 and later · before 6.12.78
linux linux kernel6.13 and later · before 6.18.20
linux linux kernel6.19 and later · before 6.19.10
linux linux kernel7.0

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
- 3.9affected
- 96d851c4d28de8cc83fe2bd5c6bc2eb8f253a6c5 and later · before 76740c28050dc6db2f5550f1325b00a11bbb3255affected · git
- 96d851c4d28de8cc83fe2bd5c6bc2eb8f253a6c5 and later · before c7f406fb341d6747634b8b1fa5461656e5e56076affected · git
- 96d851c4d28de8cc83fe2bd5c6bc2eb8f253a6c5 and later · before d1a19217995df9c7e4118f5a2820c5032fef2945affected · git
- 96d851c4d28de8cc83fe2bd5c6bc2eb8f253a6c5 and later · before e3d77f935639e6ae4b381c80464c31df998d61f4affected · git
- 96d851c4d28de8cc83fe2bd5c6bc2eb8f253a6c5 and later · before db4a9f99b12a7ee1c19d86c83a3b752c7effa6c6affected · git
- 96d851c4d28de8cc83fe2bd5c6bc2eb8f253a6c5 and later · before 6a8d70e2ad6aad2c345a5048edcb8168036f97d6affected · git
- 96d851c4d28de8cc83fe2bd5c6bc2eb8f253a6c5 and later · before e7fcf179b82d3a3730fd8615da01b087cc654d0baffected · git
- before 3.9not affected · semver
- 5.10.253 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.

Ecosystem	Package	Affected range	Fix
Debian:12	linux	before 6.1.170-1	6.1.170-1
Debian:13	linux	before 6.12.85-1	6.12.85-1
Debian:14	linux	before 6.19.10-1	6.19.10-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
90Now
CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
89Now
CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
85Now

Published before and after this one in the same product

← EarlierCVE-2026-31401Apr 3, 2026 · HID: bpf: prevent buffer overflow in hid_hw_request
31Monitor
← EarlierCVE-2026-31402Apr 3, 2026 · nfsd: fix heap overflow in NFSv4.0 LOCK replay cache
39Monitor
Later →CVE-2026-31405Apr 6, 2026 · media: dvb-net: fix OOB access in ULE extension header tables
39Monitor

Remediation

Which version to upgrade to

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

Product / package	Fixed version	Source
Linux Linux	6a8d70e2ad6aad2c345a5048edcb8168036f97d6	Vendor (CNA)
Linux Linux	76740c28050dc6db2f5550f1325b00a11bbb3255	Vendor (CNA)
Linux Linux	c7f406fb341d6747634b8b1fa5461656e5e56076	Vendor (CNA)
Linux Linux	d1a19217995df9c7e4118f5a2820c5032fef2945	Vendor (CNA)
Linux Linux	db4a9f99b12a7ee1c19d86c83a3b752c7effa6c6	Vendor (CNA)
Linux Linux	e3d77f935639e6ae4b381c80464c31df998d61f4	Vendor (CNA)
Linux Linux	e7fcf179b82d3a3730fd8615da01b087cc654d0b	Vendor (CNA)
debian:linux	6.1.170-1 · Debian:12	Package 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.

No history yet (it accumulates with the daily EPSS job).

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-secondary

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

1free(dev->buf);
2/* ... another thread is still running ... */
3process(dev->buf);

Fixed

1lock(&dev->lock);
2free(dev->buf);
3dev->buf = NULL;
4unlock(&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.

Change log

SSVC exploitation— → noneOct 16, 2026, 5:07 PM UTC
Fix✗ → ✓Sep 28, 2026, 10:11 PM UTC

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

References

git.kernel.org/stable/c/6a8d70e2ad6aad2c345a5048edcb8168036f97d6

Show all references (9 more)

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

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