CVE-2025-38407

SMP boot hang via invalid physical address

Published Jul 25, 2025 · Updated May 11, 2026

Denial of service in the Linux RISC-V SBI CPU startup path allows local users to hang secondary CPU startup on affected SMP systems. sbi_hsm_hart_start() applies __pa() to vmalloc-backed sbi_hart_boot_data and supplies the resulting invalid physical address to the new hart. The failure requires RISC-V SMP with NUMA or page-based per-CPU allocation; the affected hart remains offline rather than the entire system shutting down.

CVSS severity5.5
Medium
EPSS probability0.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in the Linux RISC-V SBI CPU startup path allows local users to hang secondary CPU startup on affected SMP systems. sbi_hsm_hart_start() applies __pa() to vmalloc-backed sbi_hart_boot_data and supplies the resulting invalid physical address to the new hart. The failure requires RISC-V SMP with NUMA or page-based per-CPU allocation; the affected hart remains offline rather than the entire system shutting down.

The record

CVE
CVE-2025-38407
Published
Jul 25, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 25, 2025CVE publishedPublication date reported by the CVE source.
  2. May 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=6.8
  2. Affected versionversion=6b9f29b81b155af023da95f560f738f29722b306 <02c725cd55eb5052b88eeaa3f60a391ef4dcaec5
  3. Affected versionversion=6b9f29b81b155af023da95f560f738f29722b306 <2b29be967ae456fc09c320d91d52278cf721be1e
  4. Affected versionversion=6b9f29b81b155af023da95f560f738f29722b306 <f5fe094f35a37adea40b2fd52c99bb1333be9b07

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=6.8; version=6b9f29b81b155af023da95f560f738f29722b306 <02c725cd55eb5052b88eeaa3f60a391ef4dcaec5; version=6b9f29b81b155af023da95f560f738f29722b306 <2b29be967ae456fc09c320d91d52278cf721be1e; version=6b9f29b81b155af023da95f560f738f29722b306 <f5fe094f35a37adea40b2fd52c99bb1333be9b07

Published CVSS scores

5.5CanonicalCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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