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CVE Record

CVE-2022-48991: mm/khugepaged: invoke MMU notifiers in shmem/file collapse paths

In the Linux kernel, the following vulnerability has been resolved: mm/khugepaged: invoke MMU notifiers in shmem/file collapse paths Any codepath that zaps page table entries must invoke MMU notifiers to ensure that secondary MMUs (like KVM) don't keep accessing pages which aren't mapped anymore. Secondary MMUs don't hold their own references to pages that are mirrored over, so failing to notify them can lead to page use-after-free. I'm marking this as addressing an issue introduced in commit f3f0e1d2150b ("khugepaged: add support of collapse for tmpfs/shmem pages"), but most of the security impact of this only came in commit 27e1f8273113 ("khugepaged: enable collapse pmd for pte-mapped THP"), which actually omitted flushes for the removal of present PTEs, not just for the removal of empty page tables.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

This is a Linux kernel memory-safety flaw. Under specific memory compaction paths, the kernel may fail to notify secondary memory managers such as KVM, which can leave them using memory that is no longer valid. Business urgency is highest for virtualization hosts, but public severity and exploit evidence are incomplete.

Executive priority

Treat as a targeted kernel maintenance priority, not an emergency based on current evidence. Prioritize internet-facing or multi-tenant virtualization infrastructure, and rely on vendor kernel updates because severity and exploitation data are not supplied.

Technical view

The issue is in khugepaged shmem/file collapse paths. Page-table entries are zapped without required MMU notifier calls, so secondary MMUs can continue accessing pages after mappings are removed, creating a possible page use-after-free. Upstream stable commits are referenced as fixes.

Likely exposure

Exposure is most plausible on Linux systems with affected kernel code paths, especially KVM or other secondary-MMU environments using tmpfs/shmem and transparent huge page collapse behavior. The source bundle does not prove exposure for every listed kernel build or downstream distribution package.

Exploitation context

The bundle does not cite active exploitation, public exploit code, or KEV listing. It describes a kernel use-after-free condition, but provides no attacker prerequisites, impact rating, or practical exploitation details.

Researcher notes

The key technical signal is missing MMU notifier invocation during khugepaged shmem/file collapse. The source states the issue was introduced around tmpfs/shmem collapse support, with stronger security impact after pte-mapped THP collapse behavior. Downstream affected ranges require vendor confirmation.

Mitigation direction

  • Identify Linux kernels and vendor packages across virtualization and container hosts.
  • Prioritize KVM or secondary-MMU hosts for vendor kernel review.
  • Apply vendor kernel updates containing the referenced stable fixes.
  • If no package is available, follow vendor guidance for backports or temporary controls.
  • Do not assume upstream version strings match downstream patched packages.

Validation and detection

  • Compare running kernel packages against vendor advisories and changelogs for CVE-2022-48991.
  • Confirm the relevant stable fix commits are present or backported.
  • Flag KVM hosts using affected kernel families for priority validation.
  • Record whether each asset is upstream-fixed, vendor-fixed, or still unknown.
Prepared
Confidence
medium
Sources
10

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-2022-48991 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
9Source 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
LinuxLinuxf3f0e1d2150b2b99da2cbdfaad000089efe9bf30, f3f0e1d2150b2b99da2cbdfaad000089efe9bf30, f3f0e1d2150b2b99da2cbdfaad000089efe9bf30, f3f0e1d2150b2b99da2cbdfaad000089efe9bf30, f3f0e1d2150b2b99da2cbdfaad000089efe9bf30, f3f0e1d2150b2b99da2cbdfaad000089efe9bf30, f3f0e1d2150b2b99da2cbdfaad000089efe9bf30, f3f0e1d2150b2b99da2cbdfaad000089efe9bf30unaffected
LinuxLinux4.8, 0, 4.9.337, 4.14.303, 4.19.270, 5.4.227, 5.10.159, 5.15.83, 6.0.13, 6.1affected
Weakness

CWE details

No CWE listed

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