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CVE Record

CVE-2023-53216: arm64: efi: Make efi_rt_lock a raw_spinlock

In the Linux kernel, the following vulnerability has been resolved: arm64: efi: Make efi_rt_lock a raw_spinlock Running a rt-kernel base on 6.2.0-rc3-rt1 on an Ampere Altra outputs the following: BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:46 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 9, name: kworker/u320:0 preempt_count: 2, expected: 0 RCU nest depth: 0, expected: 0 3 locks held by kworker/u320:0/9: #0: ffff3fff8c27d128 ((wq_completion)efi_rts_wq){+.+.}-{0:0}, at: process_one_work (./include/linux/atomic/atomic-long.h:41) #1: ffff80000861bdd0 ((work_completion)(&efi_rts_work.work)){+.+.}-{0:0}, at: process_one_work (./include/linux/atomic/atomic-long.h:41) #2: ffffdf7e1ed3e460 (efi_rt_lock){+.+.}-{3:3}, at: efi_call_rts (drivers/firmware/efi/runtime-wrappers.c:101) Preemption disabled at: efi_virtmap_load (./arch/arm64/include/asm/mmu_context.h:248) CPU: 0 PID: 9 Comm: kworker/u320:0 Tainted: G W 6.2.0-rc3-rt1 Hardware name: WIWYNN Mt.Jade Server System B81.03001.0005/Mt.Jade Motherboard, BIOS 1.08.20220218 (SCP: 1.08.20220218) 2022/02/18 Workqueue: efi_rts_wq efi_call_rts Call trace: dump_backtrace (arch/arm64/kernel/stacktrace.c:158) show_stack (arch/arm64/kernel/stacktrace.c:165) dump_stack_lvl (lib/dump_stack.c:107 (discriminator 4)) dump_stack (lib/dump_stack.c:114) __might_resched (kernel/sched/core.c:10134) rt_spin_lock (kernel/locking/rtmutex.c:1769 (discriminator 4)) efi_call_rts (drivers/firmware/efi/runtime-wrappers.c:101) [...] This seems to come from commit ff7a167961d1 ("arm64: efi: Execute runtime services from a dedicated stack") which adds a spinlock. This spinlock is taken through: efi_call_rts() \-efi_call_virt() \-efi_call_virt_pointer() \-arch_efi_call_virt_setup() Make 'efi_rt_lock' a raw_spinlock to avoid being preempted. [ardb: The EFI runtime services are called with a different set of translation tables, and are permitted to use the SIMD registers. The context switch code preserves/restores neither, and so EFI calls must be made with preemption disabled, rather than only disabling migration.]

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

This is a Linux kernel arm64 EFI runtime locking flaw. On affected systems, a local user could potentially trigger kernel-level consequences with high confidentiality, integrity, and availability impact. The source bundle does not show remote exposure or confirmed active exploitation.

Executive priority

Prioritize patching affected arm64 Linux infrastructure, especially real-time or specialized server deployments. Business urgency is high where local users, workloads, or tenants can execute code on the host.

Technical view

The issue involves efi_rt_lock in arm64 EFI runtime calls. On PREEMPT_RT kernels, a regular spinlock may sleep while EFI calls require preemption disabled because they use different translation tables and may use SIMD state. The kernel fix makes efi_rt_lock a raw_spinlock.

Likely exposure

Exposure is most relevant to arm64 Linux systems using EFI runtime services on affected kernel versions or downstream builds. The bundle specifically references RT-kernel behavior on Ampere Altra. It is not described as a network-facing vulnerability.

Exploitation context

CVSS indicates local attack, low complexity, low privileges, and no user interaction. The bundle marks KEV as false and provides no evidence of public exploitation. Treat exploitation status as unconfirmed, not active.

Researcher notes

Evidence supports a kernel locking/preemption flaw in arm64 EFI runtime paths. The supplied data does not include CWE mapping, exploit reports, or a named workaround. Validate against vendor backports rather than relying only on upstream version strings.

Mitigation direction

  • Update to a kernel build containing the referenced stable fixes.
  • Check Linux distribution advisories for backported fixes and package names.
  • Prioritize arm64 systems using EFI runtime services or real-time kernels.
  • If updates are unavailable, follow vendor guidance for supported mitigations.
  • Restrict unnecessary local account access on affected hosts.

Validation and detection

  • Inventory arm64 Linux hosts and record running kernel versions.
  • Identify systems using affected downstream kernels or RT kernel builds.
  • Check vendor kernel changelogs for the efi_rt_lock raw_spinlock fix.
  • Confirm the installed kernel includes one of the referenced stable commits.
  • Monitor kernel logs for EFI runtime or locking warnings.
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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ATT&CK lookup starting points

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CVE-2023-53216 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
1ADP providers
6Source links

SSVC decision data

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

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:H1.85.9CISA-ADP

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2023-53216Attack 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
cvssV3_1other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux4012603cbd469223f225637d265a233f034c567a, de2af657cab92afc13a4ccd8780370481ed0eb61, f75a91c82dc805af8f718ff106ec9c090234b37b, ff7a167961d1b97e0e205f245f806e564d3505e7, ff7a167961d1b97e0e205f245f806e564d3505e7unaffected
LinuxLinux6.2, 0, 5.10.175, 5.15.103, 6.1.18, 6.2.5, 6.3affected
Weakness

CWE details

No CWE listed

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