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CVE Record

CVE-2021-47567: powerpc/32: Fix hardlockup on vmap stack overflow

In the Linux kernel, the following vulnerability has been resolved: powerpc/32: Fix hardlockup on vmap stack overflow Since the commit c118c7303ad5 ("powerpc/32: Fix vmap stack - Do not activate MMU before reading task struct") a vmap stack overflow results in a hard lockup. This is because emergency_ctx is still addressed with its virtual address allthough data MMU is not active anymore at that time. Fix it by using a physical address instead.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

This Linux kernel issue affects 32-bit PowerPC systems. Under a vmap stack overflow condition, the kernel can hard lock because it references an emergency context through a virtual address while the data MMU is inactive. The documented impact is system unavailability, not data theft or privilege escalation.

Executive priority

Give this targeted attention if the organization runs 32-bit PowerPC Linux, especially in embedded or operational technology contexts. For mainstream server fleets without PowerPC, urgency is likely low, but confirm inventory before dismissing it.

Technical view

The fix changes powerpc/32 vmap stack overflow handling to use a physical address for emergency_ctx. The regression followed commit c118c7303ad5. The source bundle lists Linux affected versions and three stable kernel commits, but does not provide CVSS, CWE, exploitability, or detailed affected-range semantics.

Likely exposure

Exposure appears limited to Linux deployments running affected 32-bit PowerPC kernels. Most general x86_64 or non-PowerPC Linux fleets are not implicated by the provided evidence. Version data in the bundle is incomplete, so confirm through vendor kernel advisories or backport records.

Exploitation context

The sources do not report active exploitation, and this CVE is not marked in KEV. The described trigger is a vmap stack overflow leading to hard lockup. Treat this primarily as an availability risk unless vendor evidence says otherwise.

Researcher notes

Evidence is narrow and kernel-specific. The source bundle identifies the bug, the regression commit, and stable fixes, but lacks CVSS, CWE, proof-of-concept status, and precise version-range metadata. Avoid broader claims beyond 32-bit PowerPC Linux availability impact.

Mitigation direction

  • Identify any 32-bit PowerPC Linux systems in production or embedded environments.
  • Update to a vendor kernel containing one of the referenced stable fixes.
  • For appliances, request the vendor’s CVE-2021-47567 fix or backport status.
  • Prioritize systems where kernel lockups would affect safety, availability, or recovery time.

Validation and detection

  • Inventory kernel architecture and version across Linux assets.
  • Check whether deployed kernels include the referenced stable commit or vendor backport.
  • Review vendor advisories for exact affected and fixed package versions.
  • Correlate unexplained PowerPC hard lockups with affected kernel versions.
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-2021-47567 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
LinuxLinuxc118c7303ad528be8ff2aea8cd1ee15452c763f0, c118c7303ad528be8ff2aea8cd1ee15452c763f0, c118c7303ad528be8ff2aea8cd1ee15452c763f0, 3b234b4a6651ed6bdca94553aa0038fc7ded9271unaffected
LinuxLinux5.10, 0, 5.10.83, 5.15.6, 5.16affected
Weakness

CWE details

No CWE listed

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