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CVE Record

CVE-2024-36943: fs/proc/task_mmu: fix loss of young/dirty bits during pagemap scan

In the Linux kernel, the following vulnerability has been resolved: fs/proc/task_mmu: fix loss of young/dirty bits during pagemap scan make_uffd_wp_pte() was previously doing: pte = ptep_get(ptep); ptep_modify_prot_start(ptep); pte = pte_mkuffd_wp(pte); ptep_modify_prot_commit(ptep, pte); But if another thread accessed or dirtied the pte between the first 2 calls, this could lead to loss of that information. Since ptep_modify_prot_start() gets and clears atomically, the following is the correct pattern and prevents any possible race. Any access after the first call would see an invalid pte and cause a fault: pte = ptep_modify_prot_start(ptep); pte = pte_mkuffd_wp(pte); ptep_modify_prot_commit(ptep, pte);

HighCVSS 7.3Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A race in Linux memory-management code can discard page “recently accessed” or “modified” status while pagemap scanning applies userfaultfd write protection. A local, low-privileged process is the stated attack position. The supplied CVSS rates potential integrity and availability impact as high, but the sources do not describe demonstrated operational consequences.

Executive priority

Treat this as a high-priority kernel maintenance issue, especially on multi-user or locally shared systems. It is not supported as an active-exploitation emergency by the supplied evidence. Obtain distributor-specific version guidance, test updates, and deploy through normal expedited patching procedures.

Technical view

make_uffd_wp_pte() read a page-table entry before ptep_modify_prot_start() atomically cleared it. Concurrent access or dirtying during that gap could be overwritten when the stale entry was committed. The fix obtains and clears the entry atomically through ptep_modify_prot_start(), modifies it, then commits it.

Likely exposure

The bundle identifies Linux 6.7, 6.8.10, and 6.9-related entries as affected, but its flattened version encoding is ambiguous and includes “0.” Exposure requires a locally reachable vulnerable kernel path. Confirm exact affected and fixed package versions with each Linux distributor.

Exploitation context

The CVSS vector indicates local access, low complexity, low privileges, and no user interaction. CISA KEV status is false, and the supplied sources provide no evidence of active exploitation or a public exploit.

Researcher notes

The defect is a stale-PTE concurrency race involving preservation of young and dirty bits during userfaultfd write-protection handling. The CVSS asserts low confidentiality and high integrity and availability impact, but the bundle does not document a demonstrated impact chain, exploit, CWE, or reliable trigger conditions beyond the code race.

Mitigation direction

  • Install vendor kernel updates that incorporate one of the cited Linux stable fixes.
  • Check distribution advisories for fixed package versions applicable to every deployed kernel branch.
  • If updates must wait, reduce untrusted local access and monitor vendor guidance; no source-specific workaround is documented.

Validation and detection

  • Inventory running kernels and map versions against vendor advisories; the bundle’s affected-version encoding is ambiguous.
  • Confirm kernel source or package changelogs contain commit 74b3d66f91d9 or c70dce4982ce.
  • After updating and rebooting, verify each host runs the intended fixed vendor kernel.
  • Review hosts allowing low-privileged local workloads to reach pagemap or userfaultfd-related memory-management functionality.
Prepared
Confidence
medium
Sources
4

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

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CVE-2024-36943 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.3 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H

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.

1CVSS vectors
3Timeline events
2ADP providers
3Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.3CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H1.85.5Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.3High
CVSS 3.1 vector shape for CVE-2024-36943Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

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
LinuxLinux52526ca7fdb905a768a93f8faa418e9b988fc34b, 52526ca7fdb905a768a93f8faa418e9b988fc34bunaffected
LinuxLinux6.7, 0, 6.8.10, 6.9affected
Weakness

CWE details

No CWE listed

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