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CVE Record

CVE-2021-47091: mac80211: fix locking in ieee80211_start_ap error path

In the Linux kernel, the following vulnerability has been resolved: mac80211: fix locking in ieee80211_start_ap error path We need to hold the local->mtx to release the channel context, as even encoded by the lockdep_assert_held() there. Fix it.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2021-47091 is a Linux kernel issue in the mac80211 wireless networking subsystem. The fix corrects locking during an access-point startup error path. The provided sources do not describe business impact, exploitability, or confirmed attacks, so urgency depends on whether affected Linux kernels and wireless AP functionality are present.

Executive priority

Treat this as a targeted Linux kernel maintenance item, not a confirmed emergency. Prioritize validation where Linux systems provide wireless access-point services, then patch through normal kernel update processes once vendor applicability is confirmed.

Technical view

The vulnerability concerns ieee80211_start_ap error handling in mac80211. The kernel fix holds local->mtx while releasing the channel context, matching the existing lockdep assertion. The source bundle provides no CVSS, CWE, crash details, privilege requirements, or exploit conditions.

Likely exposure

Exposure is most relevant to Linux systems using affected kernel builds with mac80211 wireless functionality, especially AP mode. The bundle does not identify affected distributions, hardware, cloud images, or specific package versions beyond Linux kernel version and commit references.

Exploitation context

The source bundle does not show active exploitation, public exploit details, or KEV listing. It also does not establish whether exploitation is local, remote, authenticated, or only a stability issue triggered during AP startup failure handling.

Researcher notes

Evidence is sparse. The record documents a locking correction in an error path but does not provide impact analysis. Review the three upstream stable commits and downstream backports to determine affected code paths, reachable drivers, and whether the issue can cause denial of service or broader security impact.

Mitigation direction

  • Check Linux vendor or distribution advisories for applicable fixed kernel packages.
  • Prioritize systems using wireless AP mode or mac80211-based Wi-Fi drivers.
  • Apply kernel updates containing the referenced stable fixes when available.
  • If patching is delayed, reduce reliance on affected wireless AP functionality where feasible.

Validation and detection

  • Inventory Linux kernel versions on systems with Wi-Fi hardware or AP mode enabled.
  • Map installed kernels to vendor advisories for CVE-2021-47091 applicability.
  • Confirm whether mac80211 drivers are present and operational on exposed systems.
  • Verify updated kernels include one of the referenced stable commits 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-2021-47091 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
LinuxLinux295b02c4be74bebf988593b8322369513fcecf68, 295b02c4be74bebf988593b8322369513fcecf68, 295b02c4be74bebf988593b8322369513fcecf68unaffected
LinuxLinux5.10, 0, 5.10.89, 5.15.12, 5.16affected
Weakness

CWE details

No CWE listed

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