What is CVE-2025-40307?

CVE-2025-40307 is a High severity Linux kernel vulnerability with a CVSS score of 7.8 out of 10, affecting Linux kernel versions from 5.7 onward and patched in 6.1.183, 6.6.148, 6.12.58 and others. CVE-2025-40307 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2025-40307?

CVE-2025-40307 has a CVSS score of 7.8 out of 10, rated High severity. The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

Is there a patch available for CVE-2025-40307?

Yes, CVE-2025-40307 has been patched. Fixed versions include 6.1.183, 6.6.148, 6.12.58 and others. If you are running Linux kernel 5.7 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2025-40307 actively exploited?

CVE-2025-40307 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2025-40307

High

In the Linux kernel, the following vulnerability has been resolved: exfat: validate cluster allocation bits of the allocation bitmap syzbot created an exfat image with cluster bits not set for the allocation bitmap. exfat-fs reads and uses the allocation bitmap without checking this. The problem is that if the start cluster of the allocation bitmap is 6, cluster 6 can be allocated when creating a directory with mkdir. exfat zeros out this cluster in exfat_mkdir, which can delete existing entries. This can reallocate the allocated entries. In addition, the allocation bitmap is also zeroed out, so cluster 6 can be reallocated. This patch adds exfat_test_bitmap_range to validate that clusters used for the allocation bitmap are correctly marked as in-use.

Package Linux Kernel

Published 2025-12-08

Last modified 2026-08-19

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

7.8

out of 10

High

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Vector string

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

Affected versions

Linux kernel versions 5.7 and later are affected. Fixed in 6.1.183, 6.6.148, 6.12.58, 6.17.8, 6.18 and their respective stable series.

Affected from

≥ 5.7

Fixed in

✓ 6.1.183 6.1.x ✓ 6.6.148 6.6.x ✓ 6.12.58 6.12.x ✓ 6.17.8 6.17.x ✓ 6.18

References

5 total

Details

CVE ID CVE-2025-40307

Severity High

CVSS score 7.8 / 10

CVSS version 3.1

Published 2025-12-08

Modified 2026-08-19

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2025-40307?

CVE-2025-40307 is a High severity Linux kernel vulnerability with a CVSS score of 7.8 out of 10 . It affects Linux kernel versions from 5.7 onward and has been patched in 6.1.183, 6.6.148, 6.12.58 and others. CVE-2025-40307 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2025-40307?

CVE-2025-40307 has a CVSS score of 7.8 out of 10, rated High severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
Is there a patch available for CVE-2025-40307?

Yes. CVE-2025-40307 has been patched. Fixed versions include 6.1.183, 6.6.148, 6.12.58 and others. If you are running Linux kernel 5.7 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2025-40307 actively exploited?

No. CVE-2025-40307 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.