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CVE Record

CVE-2025-38169: arm64/fpsimd: Avoid clobbering kernel FPSIMD state with SMSTOP

In the Linux kernel, the following vulnerability has been resolved: arm64/fpsimd: Avoid clobbering kernel FPSIMD state with SMSTOP On system with SME, a thread's kernel FPSIMD state may be erroneously clobbered during a context switch immediately after that state is restored. Systems without SME are unaffected. If the CPU happens to be in streaming SVE mode before a context switch to a thread with kernel FPSIMD state, fpsimd_thread_switch() will restore the kernel FPSIMD state using fpsimd_load_kernel_state() while the CPU is still in streaming SVE mode. When fpsimd_thread_switch() subsequently calls fpsimd_flush_cpu_state(), this will execute an SMSTOP, causing an exit from streaming SVE mode. The exit from streaming SVE mode will cause the hardware to reset a number of FPSIMD/SVE/SME registers, clobbering the FPSIMD state. Fix this by calling fpsimd_flush_cpu_state() before restoring the kernel FPSIMD state.

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 flaw can corrupt processor state during task switching on ARM64 systems that support SME. A local, low-privileged user may be able to trigger serious confidentiality, integrity, or availability impact. ARM64 systems without SME are unaffected.

Executive priority

Prioritize remediation on SME-capable ARM64 systems exposed to untrusted local users or tenants. Other architectures and ARM64 systems without SME do not require action for this CVE. Confirm distribution-specific status before scheduling broad emergency maintenance.

Technical view

If a CPU remains in streaming SVE mode during a context switch, Linux may restore kernel FPSIMD state before SMSTOP exits that mode. The hardware then resets FPSIMD/SVE/SME registers, overwriting the restored state. The fix flushes CPU state before restoring kernel FPSIMD state.

Likely exposure

Exposure is limited to affected Linux kernels running on ARM64 hardware with SME. Exploitation requires local access with low privileges; it is not described as remotely reachable. Distribution backports may change whether a particular kernel build is vulnerable.

Exploitation context

The supplied record reports CVSS 7.8 with potential high confidentiality, integrity, and availability impact. It does not provide exploit evidence, and the CVE is not listed as KEV. Treat active exploitation as unconfirmed.

Researcher notes

The affected-version data contains commit identifiers and unusual version entries, so exact distribution exposure cannot be inferred reliably. The record names no CWE and provides no demonstrated exploitation. Root cause and correction are clear, but researchers should verify affected ranges and backports against vendor advisories.

Mitigation direction

  • Install a vendor-supported kernel containing the referenced fix or an equivalent backport.
  • Prioritize SME-capable ARM64 hosts that permit untrusted or multi-tenant local workloads.
  • Consult the Linux distribution's advisory to identify its fixed package version.
  • Restrict unnecessary local access until affected systems are updated.

Validation and detection

  • Confirm each ARM64 host's CPU supports SME; systems without SME are unaffected.
  • Record the running kernel and distribution package versions.
  • Verify the kernel includes a referenced fix or vendor-equivalent backport.
  • After updating, confirm the fixed kernel is running following reboot.
Prepared
Confidence
high
Sources
5

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

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

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CVE-2025-38169 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
4Source 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-2025-38169Attack 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
LinuxLinuxe92bee9f861b466c676f0200be3e46af7bc4ac6b, e92bee9f861b466c676f0200be3e46af7bc4ac6b, e92bee9f861b466c676f0200be3e46af7bc4ac6b, e003c485ac82a9f8de4204912ed059ac6dd4257c, 25b90cd122d546823da90b916f7c3289dfe83a99, 6.8.12, 6.9.3unaffected
LinuxLinux6.10, 0, 6.12.34, 6.15.3, 6.16affected
Weakness

CWE details

No CWE listed

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