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VulnerabilityPublished Updated

CVE-2025-38523: Linux kernel · cifs: Fix the smbd_response slab to allow usercopy

Source GCVE Database

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Not known to be exploited · CVSS 5.5 Medium.

Data as of 13 Nov 2026, 20:17 UTC

CVSS 3.1 base score
5.5Medium
How severe the flaw is on the 0–10 CVSS scale.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 16 Aug 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 13 Nov 2026.

What to do

AI-suggested

A fix is available that adjusts the smbd_response slab creation to permit usercopy from the packet region, preventing the kernel oops. Users should apply the official Linux kernel patch that implements this fix. Since this is a kernel-level issue, upgrading to a fixed kernel version is the recommended remediation. No alternative mitigations are indicated.

Description

CVE-2025-38523 is a medium severity vulnerability in the Linux kernel's CIFS client code related to the smbd_response slab cache. The flaw causes a kernel oops when CONFIG_HARDENED_USERCOPY is enabled due to improper marking of the packet field for usercopy operations. This leads to a kernel memory exposure attempt detection and a crash during data copying from the smbd_response structure to a folio buffer. The issue is fixed by adjusting slab creation parameters to allow safe usercopy from the packet region.

References

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