What is CVE-2025-40099?

CVE-2025-40099 is a Critical severity Linux kernel vulnerability with a CVSS score of 9.4 out of 10, affecting Linux kernel versions from 4.11 onward and patched in 6.1.158, 6.6.114, 6.12.55 and others. CVE-2025-40099 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2025-40099?

CVE-2025-40099 has a CVSS score of 9.4 out of 10, rated Critical severity. The vector string is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H.

Is there a patch available for CVE-2025-40099?

Yes, CVE-2025-40099 has been patched. Fixed versions include 6.1.158, 6.6.114, 6.12.55 and others. If you are running Linux kernel 4.11 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2025-40099 actively exploited?

CVE-2025-40099 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2025-40099

Critical

In the Linux kernel, the following vulnerability has been resolved: cifs: parse_dfs_referrals: prevent oob on malformed input Malicious SMB server can send invalid reply to FSCTL_DFS_GET_REFERRALS - reply smaller than sizeof(struct get_dfs_referral_rsp) - reply with number of referrals smaller than NumberOfReferrals in the header Processing of such replies will cause oob. Return -EINVAL error on such replies to prevent oob-s.

Package Linux Kernel

Published 2025-10-30

Last modified 2026-07-30

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

9.4

out of 10

Critical

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

Low

Availability

High

Vector string

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

Affected versions

Linux kernel versions 4.11 and later are affected. Fixed in 6.1.158, 6.6.114, 6.12.55, 6.17.5, 6.18 and their respective stable series.

Affected from

≥ 4.11

Fixed in

✓ 6.1.158 6.1.x ✓ 6.6.114 6.6.x ✓ 6.12.55 6.12.x ✓ 6.17.5 6.17.x ✓ 6.18

References

5 total

Details

CVE ID CVE-2025-40099

Severity Critical

CVSS score 9.4 / 10

CVSS version 3.1

Published 2025-10-30

Modified 2026-07-30

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2025-40099?

CVE-2025-40099 is a Critical severity Linux kernel vulnerability with a CVSS score of 9.4 out of 10 . It affects Linux kernel versions from 4.11 onward and has been patched in 6.1.158, 6.6.114, 6.12.55 and others. CVE-2025-40099 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2025-40099?

CVE-2025-40099 has a CVSS score of 9.4 out of 10, rated Critical severity (CVSS 3.1). The vector string is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H.
Is there a patch available for CVE-2025-40099?

Yes. CVE-2025-40099 has been patched. Fixed versions include 6.1.158, 6.6.114, 6.12.55 and others. If you are running Linux kernel 4.11 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2025-40099 actively exploited?

No. CVE-2025-40099 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.