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CVE Record

CVE-2024-43840: bpf, arm64: Fix trampoline for BPF_TRAMP_F_CALL_ORIG

In the Linux kernel, the following vulnerability has been resolved: bpf, arm64: Fix trampoline for BPF_TRAMP_F_CALL_ORIG When BPF_TRAMP_F_CALL_ORIG is set, the trampoline calls __bpf_tramp_enter() and __bpf_tramp_exit() functions, passing them the struct bpf_tramp_image *im pointer as an argument in R0. The trampoline generation code uses emit_addr_mov_i64() to emit instructions for moving the bpf_tramp_image address into R0, but emit_addr_mov_i64() assumes the address to be in the vmalloc() space and uses only 48 bits. Because bpf_tramp_image is allocated using kzalloc(), its address can use more than 48-bits, in this case the trampoline will pass an invalid address to __bpf_tramp_enter/exit() causing a kernel crash. Fix this by using emit_a64_mov_i64() in place of emit_addr_mov_i64() as it can work with addresses that are greater than 48-bits.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

On arm64 Linux systems, a faulty BPF trampoline can pass an invalid kernel pointer and crash the machine. Triggering requires local, low-privileged access under the supplied CVSS assessment and the affected BPF call path. This creates meaningful availability risk, especially on shared or business-critical hosts.

Executive priority

Prioritize exposed arm64 multi-user, shared, and availability-sensitive systems. Schedule prompt vendor-supported kernel updates, while validating actual exposure before emergency action because active exploitation is not evidenced and version boundaries are incomplete.

Technical view

With BPF_TRAMP_F_CALL_ORIG enabled, arm64 trampoline generation used emit_addr_mov_i64() for a kzalloc()-allocated bpf_tramp_image address. That emitter assumes vmalloc-space addresses and preserves only 48 bits. Higher addresses become invalid when passed to __bpf_tramp_enter() or __bpf_tramp_exit(), causing a kernel crash. The documented correction uses emit_a64_mov_i64().

Likely exposure

Exposure requires an arm64 Linux kernel containing the faulty trampoline code and use of the BPF_TRAMP_F_CALL_ORIG path. The supplied affected-version data is not sufficiently structured to establish dependable version ranges. Distribution backports may also change status, so validate the running kernel against vendor guidance and referenced fixes.

Exploitation context

The CVSS 3.1 score is 7.8 with local access, low privileges, low complexity, and no user interaction. The bundle marks this CVE as absent from KEV and provides no evidence of active exploitation. The documented outcome is a kernel crash; broader compromise is not demonstrated.

Researcher notes

The root cause and source-level correction are clearly described, but the supplied affected-version entries are ambiguous and should not be interpreted as clean ranges. Confirm ancestry or backport status per kernel build. Crash-log review can support investigation, but absence of prior crashes does not establish that a system is unaffected.

Mitigation direction

  • Apply a supported vendor kernel update incorporating the referenced stable fix.
  • Reboot affected arm64 systems into the updated kernel and confirm the running version.
  • For custom kernels, assess backporting the documented emit_a64_mov_i64() correction.
  • Check distribution guidance because the bundle does not provide reliable fixed-version boundaries.

Validation and detection

  • Inventory arm64 systems and record their running kernel packages and versions.
  • Confirm whether vendor builds backport any referenced stable fix commit.
  • Identify systems using BPF functionality capable of exercising CALL_ORIG trampolines.
  • Review kernel crash telemetry involving __bpf_tramp_enter() or __bpf_tramp_exit().
  • After remediation, verify systems booted the corrected kernel rather than merely installing it.
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

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CVE-2024-43840 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
6Source 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-2024-43840Attack 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

CISA-ADPCISA ADP Vulnrichment
other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxefc9909fdce00a827a37609628223cd45bf95d0b, efc9909fdce00a827a37609628223cd45bf95d0b, efc9909fdce00a827a37609628223cd45bf95d0b, efc9909fdce00a827a37609628223cd45bf95d0bunaffected
LinuxLinux6.0, 0, 6.1.140, 6.6.92, 6.10.3, 6.11affected
Weakness

CWE details

No CWE listed

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