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CVE Record

CVE-2023-54173: bpf: Disable preemption in bpf_event_output

In the Linux kernel, the following vulnerability has been resolved: bpf: Disable preemption in bpf_event_output We received report [1] of kernel crash, which is caused by using nesting protection without disabled preemption. The bpf_event_output can be called by programs executed by bpf_prog_run_array_cg function that disabled migration but keeps preemption enabled. This can cause task to be preempted by another one inside the nesting protection and lead eventually to two tasks using same perf_sample_data buffer and cause crashes like: BUG: kernel NULL pointer dereference, address: 0000000000000001 #PF: supervisor instruction fetch in kernel mode #PF: error_code(0x0010) - not-present page ... ? perf_output_sample+0x12a/0x9a0 ? finish_task_switch.isra.0+0x81/0x280 ? perf_event_output+0x66/0xa0 ? bpf_event_output+0x13a/0x190 ? bpf_event_output_data+0x22/0x40 ? bpf_prog_dfc84bbde731b257_cil_sock4_connect+0x40a/0xacb ? xa_load+0x87/0xe0 ? __cgroup_bpf_run_filter_sock_addr+0xc1/0x1a0 ? release_sock+0x3e/0x90 ? sk_setsockopt+0x1a1/0x12f0 ? udp_pre_connect+0x36/0x50 ? inet_dgram_connect+0x93/0xa0 ? __sys_connect+0xb4/0xe0 ? udp_setsockopt+0x27/0x40 ? __pfx_udp_push_pending_frames+0x10/0x10 ? __sys_setsockopt+0xdf/0x1a0 ? __x64_sys_connect+0xf/0x20 ? do_syscall_64+0x3a/0x90 ? entry_SYSCALL_64_after_hwframe+0x72/0xdc Fixing this by disabling preemption in bpf_event_output. [1] https://github.com/cilium/cilium/issues/26756

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A Linux kernel concurrency flaw can let two tasks reuse the same performance-event buffer, causing a kernel crash. The supplied CVSS rates it high at 7.8 and requires local, low-privileged access. The documented impact is primarily service disruption; broader confidentiality and integrity impacts are scored but not demonstrated in the supplied description.

Executive priority

Treat as a high-priority stability and local-security update, especially for shared, containerized, or BPF-intensive Linux systems. Patch through supported distribution channels after normal compatibility testing. Escalate faster where local users or workloads are less trusted, while avoiding claims of active exploitation unsupported by the supplied evidence.

Technical view

Preemption remained enabled when bpf_event_output used nesting protection from BPF programs run through the cgroup path. A task switch could allow two tasks to share perf_sample_data, leading to corruption and a NULL-pointer kernel crash. The Linux fix disables preemption within bpf_event_output.

Likely exposure

Potential exposure exists on systems running the listed affected Linux kernel versions where relevant cgroup BPF programs can invoke event output. The supplied version data is ambiguous and includes commit identifiers and isolated releases, so administrators should map distribution kernels against the referenced stable fixes rather than rely solely on version strings.

Exploitation context

The CVSS vector indicates local access, low privileges, low complexity, and no user interaction. The supplied record is not in KEV and provides no evidence of active exploitation. It documents a reported kernel crash involving Cilium, but does not establish reliable malicious exploitation or remote reachability.

Researcher notes

The demonstrated failure is a preemption-sensitive race around nesting protection and shared perf_sample_data. Stable commits are supplied, but exact affected and fixed ranges are not clearly expressed. Researchers should distinguish the documented denial-of-service crash from the CVSS confidentiality and integrity ratings, which are not substantiated by a described exploitation path here.

Mitigation direction

  • Install a vendor-supported kernel containing the applicable referenced stable fix.
  • Review Linux distribution advisories to map backported fixes to installed kernel packages.
  • Prioritize systems using cgroup BPF programs and performance-event output.
  • Restrict unnecessary local access and BPF capabilities while remediation is pending.

Validation and detection

  • Record installed kernel package versions across Linux hosts.
  • Compare vendor kernel changelogs with the five referenced stable commits.
  • Identify workloads using cgroup BPF, including relevant Cilium deployments.
  • Check kernel logs for bpf_event_output, perf_event_output, NULL dereferences, or unexplained crashes.
Prepared
Confidence
medium
Sources
8

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-2023-54173 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
0ADP providers
6Source links

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-2023-54173Attack 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.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux2a916f2f546ca1c1e3323e2a4269307f6d9890eb, 2a916f2f546ca1c1e3323e2a4269307f6d9890eb, 2a916f2f546ca1c1e3323e2a4269307f6d9890eb, 2a916f2f546ca1c1e3323e2a4269307f6d9890eb, 2a916f2f546ca1c1e3323e2a4269307f6d9890ebunaffected
LinuxLinux5.7, 0, 5.10.190, 5.15.126, 6.1.45, 6.4.10, 6.5affected
Weakness

CWE details

No CWE listed

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