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VulnerabilityPublished Updated

CVE-2025-39989: Linux kernel · x86/mce: use is_copy_from_user() to determine copy-from-user context

Affects Linux kernelSource GCVE Database

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Not known to be exploited.

Data as of 30 Oct 2026, 14:03 UTC

Severity
High

Rated High by Threat Radar's AI analysis · No CVSS score from NVD or the CNA

Thin evidence

One scorer or none

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 18 Apr 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
Linux LinuxAffected
  • =5.15.58
Fixed in–

AI-suggested

A patch series has been released to fix these regressions in memory failure handling. Users should apply the official Linux kernel updates that include the "mm/hwpoison: Fix regressions in memory failure handling" patch series to restore proper error recovery behavior. No other mitigation is required as the fix addresses the root cause.

Description

CVE-2025-39989 addresses two critical regressions in Linux kernel memory failure handling introduced since version 5.17 compared to 5.10 LTS. The first regression causes kernel panic during copy-from-user operations when poisoned memory is detected, due to incorrect exception fixup handling. The second regression leads to user process termination by SIGBUS because of a race condition between machine check interrupts related to uncorrected memory errors on Intel platforms. The patch series fixes these issues by restoring proper recovery mechanisms for memory errors during user space copying and instruction fetching.

References

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