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CVE Record

CVE-2024-36918: bpf: Check bloom filter map value size

In the Linux kernel, the following vulnerability has been resolved: bpf: Check bloom filter map value size This patch adds a missing check to bloom filter creating, rejecting values above KMALLOC_MAX_SIZE. This brings the bloom map in line with many other map types. The lack of this protection can cause kernel crashes for value sizes that overflow int's. Such a crash was caught by syzkaller. The next patch adds more guard-rails at a lower level.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A local user with limited privileges may be able to crash an affected Linux system by creating a BPF bloom-filter map with an improperly large value size. The supplied record rates this 7.8 High. It is not described as remotely exploitable, and the sources provide no evidence of attacks in the wild.

Executive priority

Treat this as an expedited kernel-maintenance issue, especially on multi-user, developer, hosting, or shared-compute systems. The documented outcome is kernel crashing, which can disrupt availability. Although the CVSS vector scores confidentiality and integrity impacts highly, the supplied description does not explain those impacts; avoid representing compromise or data theft as confirmed.

Technical view

Linux BPF bloom-filter map creation lacked a check rejecting value sizes above KMALLOC_MAX_SIZE. Sizes overflowing an integer could reach unsafe allocation handling and cause a kernel crash, as observed by syzkaller. The referenced stable-kernel patches add the missing validation. The supplied CVSS vector is local, low-complexity, low-privilege, and requires no user interaction.

Likely exposure

Exposure primarily concerns systems running affected Linux kernels where local low-privileged users can access relevant BPF functionality. Internet reachability alone does not create exposure. The supplied affected-version metadata includes 5.16, 6.1.91, 6.6.31, 6.8.10, and 6.9, but should be reconciled with distribution advisories and backport status.

Exploitation context

The vulnerability was found through syzkaller kernel fuzzing. The supplied sources document a crash condition but provide no evidence of public weaponization or active exploitation. It is not listed in CISA KEV within the bundle. Successful triggering requires local privileges according to the CVSS vector; practical reachability depends on BPF policy and kernel configuration.

Researcher notes

The core defect is missing bounds validation during BPF bloom-filter map creation. Oversized values capable of integer overflow can lead to a kernel crash. Four stable-tree commits are supplied as fixes. Version data in the bundle is unusual, including an entry of "0" and repeated commit identifiers, so fixed-versus-affected status should be verified using vendor packaging records.

Mitigation direction

  • Install a vendor-supported kernel containing the referenced bloom-filter value-size validation fix.
  • Check distribution advisories because vendors may backport fixes without changing the upstream version number.
  • Prioritize multi-user and shared-compute systems where local users may access BPF functionality.
  • Follow vendor guidance if an updated kernel is not immediately available.

Validation and detection

  • Record each system's running kernel release and distribution package revision.
  • Compare package revisions against vendor advisories and the referenced upstream stable commits.
  • Confirm patched source rejects bloom-filter map value sizes above KMALLOC_MAX_SIZE.
  • Review whether untrusted local users can access relevant BPF map-creation functionality.
  • Reboot after kernel replacement and verify the updated kernel is running.
Prepared
Confidence
medium
Sources
6

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-2024-36918 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/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
5Source 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
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2024-36918Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

CVECVE Program Container
CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux9330986c03006ab1d33d243b7cfe598a7a3c1baa, 9330986c03006ab1d33d243b7cfe598a7a3c1baa, 9330986c03006ab1d33d243b7cfe598a7a3c1baa, 9330986c03006ab1d33d243b7cfe598a7a3c1baaunaffected
LinuxLinux5.16, 0, 6.1.91, 6.6.31, 6.8.10, 6.9affected
Weakness

CWE details

No CWE listed

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