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CVE Record

CVE-2025-39864: wifi: cfg80211: fix use-after-free in cmp_bss()

In the Linux kernel, the following vulnerability has been resolved: wifi: cfg80211: fix use-after-free in cmp_bss() Following bss_free() quirk introduced in commit 776b3580178f ("cfg80211: track hidden SSID networks properly"), adjust cfg80211_update_known_bss() to free the last beacon frame elements only if they're not shared via the corresponding 'hidden_beacon_bss' pointer.

HighCVSS 8.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A flaw in Linux Wi-Fi network-record handling can reuse kernel memory after it has been freed. The supplied CVSS assessment indicates potentially serious confidentiality, integrity, and availability consequences. Exposure requires adjacent-network reachability, making Wi-Fi-enabled devices near untrusted wireless environments the primary concern.

Executive priority

Treat this as a high-priority endpoint and appliance patching issue, especially where Linux Wi-Fi devices operate in public or hostile locations. It does not currently warrant an active-exploitation emergency designation from the supplied evidence. Require vendor-confirmed remediation and track exceptions where Wi-Fi cannot be disabled or kernels cannot be promptly updated.

Technical view

The cfg80211 subsystem mishandles ownership of beacon-frame elements shared through hidden_beacon_bss. During cfg80211_update_known_bss(), memory could be freed while still referenced by cmp_bss(), producing a kernel use-after-free. CVSS 3.1 scores it 8.8 with adjacent access, low complexity, no privileges, and no user interaction. The sources do not establish a specific exploitation outcome.

Likely exposure

Likely exposure is limited to Linux systems running vulnerable kernel code with Wi-Fi functionality present or enabled. The bundle lists several kernel branch versions but does not clearly express all affected range boundaries. Confirm status using the system vendor or distribution advisory instead of relying solely on upstream version numbers.

Exploitation context

The CVSS vector identifies an adjacent attack surface, not an internet-routable one. The bundle marks this CVE as absent from KEV and provides no evidence of active exploitation, public exploit availability, or demonstrated reliability. Practical triggering conditions beyond the affected Wi-Fi code path are not documented in the supplied evidence.

Researcher notes

The critical detail is shared ownership of the last beacon-frame elements through hidden_beacon_bss after the earlier bss_free() behavior change. Multiple stable-branch commits are referenced. Exact vulnerable and fixed boundaries are insufficiently represented in the bundle, so branch-specific commit ancestry and distribution backports should be checked. No CWE, reproducer, exploit evidence, or detailed trigger sequence is supplied.

Mitigation direction

  • Inventory Linux devices with Wi-Fi hardware or cfg80211 functionality and record their running kernel packages.
  • Apply vendor-supported kernels containing the applicable upstream stable fix.
  • Prioritize mobile endpoints and systems operating near untrusted wireless networks.
  • Temporarily disable unnecessary Wi-Fi interfaces where operationally acceptable until updates are completed.
  • Consult distribution or appliance vendors when fixed-package status is unclear.

Validation and detection

  • Confirm the running kernel package is identified as fixed by the relevant vendor advisory.
  • Verify systems rebooted into the updated kernel rather than retaining the vulnerable kernel in memory.
  • Check that vulnerable older kernels are not selected by default during startup.
  • Reinventory Wi-Fi-enabled assets after remediation to identify missed or unmanaged systems.
  • Review kernel crash telemetry for cfg80211-related faults without treating absence as proof of safety.
Prepared
Confidence
medium
Sources
12

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-2025-39864 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
8.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/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
3ADP providers
13Source links

SSVC decision data

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

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
8.8CVSS 3.1HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H2.85.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

8.8High
CVSS 3.1 vector shape for CVE-2025-39864Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

CVECVE Program Container
siemens-SADPADP container
CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux3ab8227d3e7d1d2bf1829675d3197e3cb600e9f6, 3ab8227d3e7d1d2bf1829675d3197e3cb600e9f6, 3ab8227d3e7d1d2bf1829675d3197e3cb600e9f6, 3ab8227d3e7d1d2bf1829675d3197e3cb600e9f6, 3ab8227d3e7d1d2bf1829675d3197e3cb600e9f6, 3ab8227d3e7d1d2bf1829675d3197e3cb600e9f6, 3ab8227d3e7d1d2bf1829675d3197e3cb600e9f6, 3ab8227d3e7d1d2bf1829675d3197e3cb600e9f6unaffected
LinuxLinux5.4, 0, 5.4.299, 5.10.243, 5.15.192, 6.1.151, 6.6.105, 6.12.46, 6.16.6, 6.17affected
Weakness

CWE details

No CWE listed

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