Linux Kernel up to 7.0-rc4 NFSD /proc/fs/nfs/exports exports_proc_open file descriptor consumption

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CTI Interest Score
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6.6$0-$5k0.00

Summaryinfo

A vulnerability was found in Linux Kernel up to 7.0-rc4. It has been declared as critical. This issue affects the function exports_proc_open of the file /proc/fs/nfs/exports of the component NFSD. Such manipulation leads to file descriptor consumption. This vulnerability is uniquely identified as CVE-2026-31403. No exploit exists. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 7.0-rc4 and classified as critical. Affected by this issue is the function exports_proc_open of the file /proc/fs/nfs/exports of the component NFSD. The manipulation with an unknown input leads to a file descriptor consumption vulnerability. Using CWE to declare the problem leads to CWE-769. This entry has been deprecated because it was a duplicate of CWE-774. All content has been transferred to CWE-774. Impacted is availability. CVE summarizes:

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.

The advisory is shared for download at git.kernel.org. This vulnerability is handled as CVE-2026-31403 since 03/09/2026. There are known technical details, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 313522 (Amazon Linux 2023 : bpftool, kernel, kernel-devel (ALAS2023-2026-1681)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.1.167, 6.6.130, 6.12.78, 6.18.20, 6.19.10 or 7.0-rc5 eliminates this vulnerability. Applying the patch c7f406fb341d6747634b8b1fa5461656e5e56076/d1a19217995df9c7e4118f5a2820c5032fef2945/e3d77f935639e6ae4b381c80464c31df998d61f4/db4a9f99b12a7ee1c19d86c83a3b752c7effa6c6/6a8d70e2ad6aad2c345a5048edcb8168036f97d6/e7fcf179b82d3a3730fd8615da01b087cc654d0b 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 (313522) and EUVD (EUVD-2026-18788). Once again VulDB remains the best source for vulnerability data.

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.7
VulDB Meta Temp Score: 6.6

VulDB Base Score: 5.7
VulDB Temp Score: 5.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.8
CNA Vector (Linux): 🔒

CVSSv2info

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: File descriptor consumption
CWE: CWE-769 / CWE-400 / CWE-404
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: 313522
Nessus Name: Amazon Linux 2023 : bpftool, kernel, kernel-devel (ALAS2023-2026-1681)

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.1.167/6.6.130/6.12.78/6.18.20/6.19.10/7.0-rc5
Patch: c7f406fb341d6747634b8b1fa5461656e5e56076/d1a19217995df9c7e4118f5a2820c5032fef2945/e3d77f935639e6ae4b381c80464c31df998d61f4/db4a9f99b12a7ee1c19d86c83a3b752c7effa6c6/6a8d70e2ad6aad2c345a5048edcb8168036f97d6/e7fcf179b82d3a3730fd8615da01b087cc654d0b

Timelineinfo

03/09/2026 CVE reserved
04/03/2026 +24 days Advisory disclosed
04/03/2026 +0 days VulDB entry created
05/20/2026 +47 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-31403 (🔒)
GCVE (CVE): GCVE-0-2026-31403
GCVE (VulDB): GCVE-100-355172
EUVD: 🔒

Entryinfo

Created: 04/03/2026 18:18
Updated: 05/20/2026 21:28
Changes: 04/03/2026 18:18 (60), 04/03/2026 23:10 (1), 05/10/2026 01:13 (2), 05/20/2026 21:28 (11)
Complete: 🔍
Cache ID: 216::103

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