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CVE Record

CVE-2025-39872: hsr: hold rcu and dev lock for hsr_get_port_ndev

In the Linux kernel, the following vulnerability has been resolved: hsr: hold rcu and dev lock for hsr_get_port_ndev hsr_get_port_ndev calls hsr_for_each_port, which need to hold rcu lock. On the other hand, before return the port device, we need to hold the device reference to avoid UaF in the caller function.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2025-39872 is a Linux kernel flaw in the HSR networking code. The source describes missing locking and reference handling that could let code use a network device after it should no longer be trusted. Business urgency is unclear because no severity score, impact rating, or active exploitation evidence is provided.

Executive priority

Treat this as a kernel maintenance item with uncertain severity. Prioritize validation for systems using HSR networking, then patch through normal kernel update channels unless your Linux vendor assigns higher urgency.

Technical view

The issue is in hsr_get_port_ndev. It calls hsr_for_each_port without holding the required RCU lock, and it returned a port device without taking a device reference. The kernel fix adds the needed locking/reference protection to avoid a use-after-free condition in callers.

Likely exposure

Exposure appears limited to Linux systems running affected kernel versions where the HSR networking subsystem is present or usable. The bundle lists Linux kernel version records including 6.14, 6.12.64, 6.16.8, and 6.17, but distribution-specific affected ranges are not provided.

Exploitation context

The supplied sources do not report exploitation in the wild, and CISA KEV status is false. They also do not describe attacker prerequisites, attack vector, or whether exploitation is practical from local, adjacent, or remote contexts.

Researcher notes

The public record is sparse: no CVSS, CWE, exploitability notes, or detailed affected distribution matrix are included. Analysis should center on the referenced kernel commits and downstream vendor backports rather than assumptions about exploit reachability.

Mitigation direction

  • Check Linux vendor advisories for patched kernel packages covering CVE-2025-39872.
  • Update affected kernels to vendor-supported fixed builds when available.
  • Prioritize hosts using or exposing HSR networking features.
  • If HSR is unnecessary, review whether it can be disabled per vendor guidance.

Validation and detection

  • Inventory Linux kernel versions across servers, appliances, and embedded systems.
  • Identify systems with HSR networking modules, interfaces, or related configuration.
  • Compare installed kernels against vendor CVE-2025-39872 advisories.
  • Confirm deployed kernels include one of the referenced stable fixes or vendor backports.
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-2025-39872 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
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.

0CVSS vectors
3Timeline events
0ADP providers
4Source links

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.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxef964411c8ca775967355d855abc56aeaca3c867, 9c10dd8eed74de9e8adeb820939f8745cd566d4a, 9c10dd8eed74de9e8adeb820939f8745cd566d4a, 6.12.63unaffected
LinuxLinux6.14, 0, 6.12.64, 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.