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CVE Record

CVE-2024-44948: x86/mtrr: Check if fixed MTRRs exist before saving them

In the Linux kernel, the following vulnerability has been resolved: x86/mtrr: Check if fixed MTRRs exist before saving them MTRRs have an obsolete fixed variant for fine grained caching control of the 640K-1MB region that uses separate MSRs. This fixed variant has a separate capability bit in the MTRR capability MSR. So far all x86 CPUs which support MTRR have this separate bit set, so it went unnoticed that mtrr_save_state() does not check the capability bit before accessing the fixed MTRR MSRs. Though on a CPU that does not support the fixed MTRR capability this results in a #GP. The #GP itself is harmless because the RDMSR fault is handled gracefully, but results in a WARN_ON(). Add the missing capability check to prevent this.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysislow

Security readout for executives and security teams

Plain-English summary

This Linux kernel issue can trigger a kernel warning on some x86 CPUs when the kernel checks older memory-type registers. The fault is described as handled gracefully, so business impact appears limited. Patch through normal kernel maintenance rather than emergency response unless your vendor rates it higher.

Executive priority

Handle in the next routine Linux patch cycle. Prioritize internet-facing or regulated systems only if vendor guidance raises severity. Current evidence supports low urgency because the reported outcome is a handled warning, not confirmed compromise.

Technical view

mtrr_save_state() accessed fixed MTRR MSRs without first checking the fixed-MTRR capability bit. On CPUs without that capability, RDMSR can raise a #GP. The source says the #GP is harmless and handled gracefully, but it causes WARN_ON(). Stable kernel fixes add the missing capability check.

Likely exposure

Exposure is limited to affected Linux kernel versions on x86 systems, especially CPUs lacking fixed MTRR support. The source lists multiple affected kernel lines, but distribution backports may change status. Appliances or embedded systems using Linux should be checked against vendor advisories.

Exploitation context

No KEV listing and no provided source reports active exploitation. The public description does not indicate remote attack, privilege escalation, or data exposure. The documented effect is a handled processor fault leading to a kernel warning.

Researcher notes

This is a correctness fix in x86 MTRR handling. The key condition is absence of fixed MTRR capability while MTRR exists. Avoid assuming broad exploitability; the CVE text explicitly calls the #GP harmless and gracefully handled. Validate branch-specific fixes through kernel stable commits or distro backports.

Mitigation direction

  • Apply the fixed Linux kernel for your maintained branch.
  • Use distribution security updates where available, including Debian LTS updates if applicable.
  • For appliances or embedded products, follow the vendor’s advisory and firmware guidance.
  • If no vendor package is available, track the referenced stable kernel commits.

Validation and detection

  • Inventory Linux kernel versions across x86 systems.
  • Confirm whether your running kernel includes the stable fix or vendor backport.
  • Review vendor advisories for Debian, Siemens, or affected appliance suppliers as applicable.
  • Check kernel logs for related x86/mtrr WARN_ON messages if investigating symptoms.
Prepared
Confidence
medium
Sources
7

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.

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CVE-2024-44948 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
3ADP providers
12Source 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
siemens-SADPADP container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux2b1f6278d77c1f2f669346fc2bb48012b5e9495a, 2b1f6278d77c1f2f669346fc2bb48012b5e9495a, 2b1f6278d77c1f2f669346fc2bb48012b5e9495a, 2b1f6278d77c1f2f669346fc2bb48012b5e9495a, 2b1f6278d77c1f2f669346fc2bb48012b5e9495a, 2b1f6278d77c1f2f669346fc2bb48012b5e9495a, 2b1f6278d77c1f2f669346fc2bb48012b5e9495a, 2b1f6278d77c1f2f669346fc2bb48012b5e9495aunaffected
LinuxLinux2.6.22, 0, 4.19.320, 5.4.282, 5.10.224, 5.15.165, 6.1.105, 6.6.46, 6.10.5, 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.