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CVE Record

CVE-2024-46838: userfaultfd: don't BUG_ON() if khugepaged yanks our page table

In the Linux kernel, the following vulnerability has been resolved: userfaultfd: don't BUG_ON() if khugepaged yanks our page table Since khugepaged was changed to allow retracting page tables in file mappings without holding the mmap lock, these BUG_ON()s are wrong - get rid of them. We could also remove the preceding "if (unlikely(...))" block, but then we could reach pte_offset_map_lock() with transhuge pages not just for file mappings but also for anonymous mappings - which would probably be fine but I think is not necessarily expected.

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 is a reliability and availability risk. A kernel assertion in userfaultfd can be reached after a legitimate memory-management race with khugepaged, causing the kernel to hit BUG_ON instead of handling the condition. The public record does not provide CVSS, CWE, or confirmed exploitation evidence.

Executive priority

Treat as a kernel maintenance item with availability impact, not a confirmed emergency. Patch through normal accelerated kernel update channels, especially where Linux hosts support shared workloads or high-availability services.

Technical view

The flaw is in Linux userfaultfd handling when khugepaged retracts page tables for file mappings without the mmap lock. Existing BUG_ON checks became invalid after that behavior change. The stable fix removes those BUG_ON paths rather than treating the condition as impossible.

Likely exposure

Exposure is limited to Linux systems running affected kernel builds described in the CVE record, including 6.6-era kernels before relevant stable fixes. Distribution backports may change version appearance, so package-level verification is required.

Exploitation context

The provided sources do not show active exploitation, KEV listing, exploit maturity, privilege requirements, or attack vector. Because BUG_ON can crash a kernel, the main concern is potential denial of service if the condition is reachable.

Researcher notes

The record lacks CVSS, CWE, and exploitability details. Analysis should focus on commit inclusion, affected stable branches, and whether local userfaultfd availability changes practical exposure in each environment. Avoid assuming remote exploitability from the public data.

Mitigation direction

  • Check your Linux distribution advisory for CVE-2024-46838.
  • Update to a kernel containing the referenced stable fixes.
  • Prioritize internet-facing or multi-tenant Linux hosts first.
  • If patching is delayed, monitor vendor guidance for supported mitigations.

Validation and detection

  • Inventory Linux kernel versions across servers and images.
  • Map each kernel package to vendor CVE status.
  • Confirm whether referenced stable commits are included or backported.
  • Review crash logs for BUG_ON events in userfaultfd or memory-management paths.
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-2024-46838 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
1ADP 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

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux1d65b771bc08cd054cf6d3766a72e113dc46d62f, 1d65b771bc08cd054cf6d3766a72e113dc46d62f, 1d65b771bc08cd054cf6d3766a72e113dc46d62funaffected
LinuxLinux6.6, 0, 6.6.51, 6.10.10, 6.11affected
Weakness

CWE details

No CWE listed

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