What is CVE-2026-89640?

CVE-2026-89640 is a High severity Linux kernel vulnerability with a CVSS score of 7.1 out of 10, affecting Linux kernel versions from 4.5 onward and patched in 6.1.188, 6.6.157, 6.12.109 and others. CVE-2026-89640 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2026-89640?

CVE-2026-89640 has a CVSS score of 7.1 out of 10, rated High severity. The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H.

Is there a patch available for CVE-2026-89640?

Yes, CVE-2026-89640 has been patched. Fixed versions include 6.1.188, 6.6.157, 6.12.109 and others. If you are running Linux kernel 4.5 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2026-89640 actively exploited?

CVE-2026-89640 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2026-89640

High

In the Linux kernel, the following vulnerability has been resolved: cifs: fix loff_t underflow in cifs_remap_file_range() when len == 0 With len == 0 (clone to EOF), the effective length is computed as: len = src_inode->i_size - off; If off > i_size, this is a negative loff_t, corrupting the ByteCount in the FSCTL_DUPLICATE_EXTENTS_TO_FILE request and inverting the range in filemap_write_and_wait_range(). The existing off >= i_size check fires only after the ioctl has already been sent. Snapshot i_size_read() once for both the bounds check and the length calculation, eliminating the TOCTOU and 32-bit torn-read risk. Reject off > src_size with -EINVAL. Treat off == src_size as a no-op, consistent with __generic_remap_file_range_prep().

Package Linux Kernel

Published 2026-09-11

Last modified 2026-09-14

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

7.1

out of 10

High

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

High

Availability

High

Vector string

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

Affected versions

Linux kernel versions 4.5 and later are affected. Fixed in 6.1.188, 6.6.157, 6.12.109, 6.18.50, 7.2.4, 7.3-rc1 and their respective stable series.

Affected from

≥ 4.5

Fixed in

✓ 6.1.188 6.1.x ✓ 6.6.157 6.6.x ✓ 6.12.109 6.12.x ✓ 6.18.50 6.18.x ✓ 7.2.4 7.2.x ✓ 7.3-rc1

References

6 total

Showing 5 of 6 references View all on NVD

Details

CVE ID CVE-2026-89640

Severity High

CVSS score 7.1 / 10

CVSS version 3.1

Published 2026-09-11

Modified 2026-09-14

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2026-89640?

CVE-2026-89640 is a High severity Linux kernel vulnerability with a CVSS score of 7.1 out of 10 . It affects Linux kernel versions from 4.5 onward and has been patched in 6.1.188, 6.6.157, 6.12.109 and others. CVE-2026-89640 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2026-89640?

CVE-2026-89640 has a CVSS score of 7.1 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:N/I:H/A:H.
Is there a patch available for CVE-2026-89640?

Yes. CVE-2026-89640 has been patched. Fixed versions include 6.1.188, 6.6.157, 6.12.109 and others. If you are running Linux kernel 4.5 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2026-89640 actively exploited?

No. CVE-2026-89640 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.