Security readout for executives and security teams
Plain-English summary
A Linux NFS server can crash when a pNFS client sends a LAYOUTCOMMIT operation for a FlexFiles layout. The documented impact is service availability, not data theft or modification. Business risk is highest where affected NFS services are reachable by untrusted clients.
Executive priority
Treat this as a high-priority availability issue for FlexFiles NFSD servers reachable by untrusted clients. Inventory those systems promptly and remediate through supported kernel updates. Systems not serving the affected layout are outside the primary exposure described by the sources.
Technical view
Linux NFSD lacked the required proc_layoutcommit handling for the FlexFiles layout type. A network client can trigger a server crash through a LAYOUTCOMMIT operation. CVSS 3.1 scores this 7.5: network-accessible, low complexity, no privileges or user interaction, with high availability impact and no stated confidentiality or integrity impact.
Likely exposure
Likely exposure is limited to Linux systems operating as NFSD servers and offering FlexFiles pNFS layouts. Exact affected distribution packages cannot be determined reliably from the supplied version data, which includes commit identifiers and unusual version entries. Confirm exposure through vendor-specific kernel mappings.
Exploitation context
The supplied sources do not report active exploitation, and the CVE is not identified as KEV. The CVSS vector indicates a network-reachable, unauthenticated, low-complexity availability attack. This describes potential exploitability, not evidence that attacks are occurring.
Researcher notes
The record describes a crash prevented by defining proc_layoutcommit for FlexFiles and provides eight stable-tree commits. Its affected-version data is ambiguous, including repeated commit hashes and an unusual “0” entry; do not infer precise fixed ranges without upstream or distribution confirmation. No CWE or public exploitation evidence is supplied.
Mitigation direction
- Apply a supported vendor kernel update containing the applicable referenced Linux stable fix.
- Consult distribution guidance to map packaged kernels to the upstream fixes before declaring systems remediated.
- Prioritize FlexFiles NFSD servers reachable from untrusted networks or clients.
Validation and detection
- Confirm whether each host runs Linux NFSD and offers the FlexFiles pNFS layout.
- Record the running kernel package, version, distribution, and build revision.
- Map each build to a referenced stable commit or authoritative vendor advisory.
- Review kernel logs for unexplained NFSD crashes; absence of crashes does not prove non-exposure.
- After updating, verify the running kernel contains the applicable fix and NFSD operates normally.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
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CVE-2025-40087 mapping review
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Open ATT&CK lookup- Severity
- High
- CVSS
- 7.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6LinuxVulnerability scoring details
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
Source materials
- CVE List V5 sourceCVE List V5
- https://git.kernel.org/stable/c/a75994dd879401c3e24ff51c2536559f1a53ea27CVE reference, Linux
- https://git.kernel.org/stable/c/34d187e020cbda112a6c6f094f0ca5e6a8672b75CVE reference, Linux
- https://git.kernel.org/stable/c/ba88a53d7f5df4191583abf214214efe0cda91d2CVE reference, Linux
- https://git.kernel.org/stable/c/da9129ef77786839a3ccd1d7afeeab790bceaa1dCVE reference, Linux
- https://git.kernel.org/stable/c/f7353208c91ab004e0179c5fb6c365b0f132f9f0CVE reference, Linux
- https://git.kernel.org/stable/c/a156af6a4dc38c2aa7c98e89520a70fb3b3e7df4CVE reference, Linux
- https://git.kernel.org/stable/c/785ec512afa80d0540f2ca797c0e56de747a6083CVE reference, Linux
- https://git.kernel.org/stable/c/4b47a8601b71ad98833b447d465592d847b4dc77CVE reference, Linux
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.