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CVE Record

CVE-2025-39926: genetlink: fix genl_bind() invoking bind() after -EPERM

In the Linux kernel, the following vulnerability has been resolved: genetlink: fix genl_bind() invoking bind() after -EPERM Per family bind/unbind callbacks were introduced to allow families to track multicast group consumer presence, e.g. to start or stop producing events depending on listeners. However, in genl_bind() the bind() callback was invoked even if capability checks failed and ret was set to -EPERM. This means that callbacks could run on behalf of unauthorized callers while the syscall still returned failure to user space. Fix this by only invoking bind() after "if (ret) break;" check i.e. after permission checks have succeeded.

MediumCVSS 5.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This Linux kernel flaw lets an unauthorized local caller trigger Generic Netlink bind callbacks even though permission checks reject the request. The direct business risk is service disruption, not data theft. Systems with shared local access, workloads from multiple tenants, or containerized untrusted code deserve priority.

Executive priority

Treat this as a targeted operational-risk patch, not an emergency internet-wide exposure. Prioritize multi-user Linux infrastructure and container hosts because the impact centers on local availability disruption.

Technical view

Generic Netlink genl_bind() could call per-family bind callbacks after capability checks had already set -EPERM. User space still saw failure, but kernel callbacks could run for unauthorized callers. The CVSS vector indicates local access, low privileges, no confidentiality or integrity impact, and high availability impact.

Likely exposure

Exposure is local: an already-authenticated low-privileged user or process on an affected Linux kernel. Public data names Linux kernel versions and stable commits, but not distribution packages. Internet-facing network exposure alone is not indicated.

Exploitation context

The source bundle does not report active exploitation, and KEV status is false. The described condition is a permission-check ordering bug with potential unauthorized callback side effects. No source identifies weaponized exploitation, affected distributions, or specific vulnerable Generic Netlink families.

Researcher notes

The key issue is callback execution despite failed authorization in genl_bind(). Evidence does not name specific affected Generic Netlink families or callback side effects, so validate exposure through kernel provenance and vendor backport status rather than assumptions.

Mitigation direction

  • Apply Linux vendor or stable kernel updates that include the referenced genetlink fixes.
  • Prioritize shared systems, container hosts, and servers allowing untrusted local users.
  • Restrict local shell access and untrusted container execution where patching is delayed.
  • Monitor vendor advisories for distribution-specific fixed package versions.

Validation and detection

  • Inventory Linux kernel versions across servers, workstations, and container hosts.
  • Compare deployed kernels with vendor advisories and the referenced stable fixes.
  • Identify systems where low-privileged local users or untrusted workloads can execute code.
  • Track remediation evidence through package version, kernel build, or vendor backport notes.
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.

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CVE-2025-39926 mapping review

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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-2025-39926Attack 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
LinuxLinux3de21a8990d3c2cc507e9cc4ed00f36358d5b93e, 3de21a8990d3c2cc507e9cc4ed00f36358d5b93e, 3de21a8990d3c2cc507e9cc4ed00f36358d5b93eunaffected
LinuxLinux6.9, 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.