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VulnerabilityPublished Updated

CVE-2025-40099: Linux kernel · cifs: parse_dfs_referrals: prevent oob on malformed input

Source GCVE Database

0

Not known to be exploited · CVSS 9.4 Critical.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score
9.4Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.4% chance of exploitation in 30 days – higher than 34% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 30 Oct 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: 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 26 Oct 2026.

What to do

AI-suggested

A fix has been implemented in the Linux kernel to return an error (-EINVAL) on malformed DFS referral replies, preventing out-of-bounds memory access. Users should update their Linux kernel to a version that includes this fix. Patch status is not explicitly confirmed in the provided data; therefore, check the official Linux kernel advisories or vendor updates for the exact fixed versions and apply them accordingly.

Description

A critical vulnerability in the Linux kernel's CIFS client was resolved to prevent out-of-bounds (OOB) memory access caused by malformed input from malicious SMB servers. Specifically, invalid replies to FSCTL_DFS_GET_REFERRALS with improperly sized data or inconsistent referral counts could trigger OOB conditions. The fix involves returning an error (-EINVAL) when such malformed replies are detected, preventing OOB memory access.

References

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