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CVE Record

CVE-2025-39912: nfs/localio: restore creds before releasing pageio data

In the Linux kernel, the following vulnerability has been resolved: nfs/localio: restore creds before releasing pageio data Otherwise if the nfsd filecache code releases the nfsd_file immediately, it can trigger the BUG_ON(cred == current->cred) in __put_cred() when it puts the nfsd_file->nf_file->f-cred.

MediumCVSS 5.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2025-39912 is a Linux kernel availability issue in NFS localio handling. A local user with low privileges may trigger a kernel BUG condition, potentially crashing or disrupting the system. The public data does not show CISA KEV listing or active exploitation.

Executive priority

Handle in normal vulnerability maintenance cycles, with faster remediation for shared Linux systems or NFS infrastructure where local users are not fully trusted. Business impact is primarily service disruption, not data theft, based on the provided CVSS and description.

Technical view

The flaw involves NFS localio credential handling. Credentials were not restored before releasing pageio data, so immediate release through nfsd filecache can hit BUG_ON(cred == current->cred) in __put_cred() when f_cred is put. The CVSS vector indicates local, low-complexity, low-privilege denial of service.

Likely exposure

Exposure is most relevant to Linux systems running affected kernel versions and using the NFS/localio/nfsd code path. The CVE data lists Linux kernel versions including 6.12, 6.12.48, 6.16.8, and 6.17 as affected, with other statuses requiring vendor verification.

Exploitation context

The CVSS vector requires local access and low privileges, with no user interaction. Public sources in the bundle do not state active exploitation, and kev is false. Treat this as a local denial-of-service risk, not a confirmed remote compromise issue.

Researcher notes

Evidence is limited to the CVE record and Linux stable commit references. The affected-version data appears kernel-specific and should be normalized against distribution backports. No CWE, proof-of-concept, exploit-in-the-wild claim, or vendor workaround is provided in the source bundle.

Mitigation direction

  • Apply a vendor kernel update that includes the referenced stable Linux fixes.
  • Check Linux distribution advisories for backported fixed package versions.
  • Prioritize NFS-capable hosts where untrusted local users have accounts.
  • Plan reboot requirements after kernel package installation.
  • Limit unnecessary local shell access on affected NFS hosts.

Validation and detection

  • Inventory Linux kernel versions across NFS servers and clients.
  • Check whether deployed kernels include the referenced stable commits.
  • Review distribution changelogs for CVE-2025-39912 backports.
  • Confirm NFS/localio exposure on systems with local multi-user access.
  • Track vendor advisory status until patched kernels are confirmed.
Prepared
Confidence
medium
Sources
5

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

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-2025-39912 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
5.5 (3.1)
Known Exploited
No
Published

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

Official CVE source material

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.

1CVSS vectors
3Timeline events
1ADP providers
4Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

CVSS vector scores

1 official score

We 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.

ScoreVersionSeverityVectorExploitImpactSource
5.5CVSS 3.1MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H1.83.6CISA-ADP

Vulnerability scoring details

Base CVSS 3.1 score

5.5Medium
CVSS 3.1 vector shape for CVE-2025-39912Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
cvssV3_1other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxb9f5dd57f4a52990963eeb1f1b58d00f717ece69, b9f5dd57f4a52990963eeb1f1b58d00f717ece69, b9f5dd57f4a52990963eeb1f1b58d00f717ece69unaffected
LinuxLinux6.12, 0, 6.12.48, 6.16.8, 6.17affected
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.