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CVE Record

CVE-2021-47251: mac80211: fix skb length check in ieee80211_scan_rx()

In the Linux kernel, the following vulnerability has been resolved: mac80211: fix skb length check in ieee80211_scan_rx() Replace hard-coded compile-time constants for header length check with dynamic determination based on the frame type. Otherwise, we hit a validation WARN_ON in cfg80211 later. [style fixes, reword commit message]

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

A Linux kernel Wi-Fi scanning bug could make the kernel hit an internal validation warning when processing certain 802.11 scan frames. The public record does not provide CVSS, CWE, confirmed exploitation, or detailed impact, so business urgency depends on where affected wireless-capable Linux kernels are deployed.

Executive priority

Handle through normal kernel patch management unless the organization operates many Wi-Fi-enabled Linux endpoints or embedded devices. There is no source-backed evidence of active exploitation or severe impact, but kernel wireless bugs deserve timely remediation on exposed fleets.

Technical view

CVE-2021-47251 concerns mac80211 ieee80211_scan_rx(). The fix replaces hard-coded header length constants with dynamic frame-type-based length determination, avoiding a later cfg80211 WARN_ON. Sources identify Linux kernel versions including 5.10, 5.10.46, 5.12.13, and 5.13 as affected, with stable commits referenced as fixes.

Likely exposure

Exposure is most plausible on Linux systems using the mac80211 wireless stack and scan handling. Servers, containers, or appliances without Wi-Fi hardware or disabled wireless functionality are likely less exposed, but vendor backports may change version-based conclusions.

Exploitation context

The supplied sources do not show active exploitation, public exploit availability, KEV listing, or a full attack impact description. Treat exploitation status as unconfirmed. The described failure is a kernel validation warning related to malformed or unexpected scan-frame length handling.

Researcher notes

The record is sparse: no CVSS, CWE, exploit status, or detailed impact is provided. Focus analysis on the upstream stable commits and downstream vendor backports. Avoid assuming remote code execution, privilege escalation, or denial-of-service beyond the described WARN_ON behavior.

Mitigation direction

  • Check Linux distribution advisories for CVE-2021-47251 coverage.
  • Update affected kernels to vendor-fixed builds or stable kernels containing the referenced commits.
  • Prioritize laptops, workstations, embedded devices, and appliances with Wi-Fi enabled.
  • Disable unused wireless interfaces where operationally acceptable.
  • Track vendor backport notes rather than relying only on upstream version numbers.

Validation and detection

  • Inventory Linux kernel versions across wireless-capable assets.
  • Identify systems with mac80211-based Wi-Fi drivers or enabled wireless scanning.
  • Confirm whether vendor kernel packages include the referenced stable fixes.
  • Review kernel logs for recurring cfg80211 or mac80211 WARN_ON events.
  • Document exceptions for systems without Wi-Fi hardware or disabled wireless functionality.
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-2021-47251 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
2ADP providers
4Source links

SSVC decision data

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

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
other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxcd418ba63f0c2f6157f35a41c9accc6ecb52590a, cd418ba63f0c2f6157f35a41c9accc6ecb52590a, cd418ba63f0c2f6157f35a41c9accc6ecb52590aunaffected
LinuxLinux5.10, 0, 5.10.46, 5.12.13, 5.13affected
Weakness

CWE details

No CWE listed

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