What is CVE-2026-89639?

CVE-2026-89639 is a High severity Linux kernel vulnerability with a CVSS score of 7.1 out of 10, affecting Linux kernel versions from 6.18.44 onward and patched in 6.18.50, 7.2.4 and 7.3-rc1. CVE-2026-89639 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2026-89639?

CVE-2026-89639 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:H/I:H/A:N.

Is there a patch available for CVE-2026-89639?

Yes, CVE-2026-89639 has been patched. Fixed versions include 6.18.50, 7.2.4 and 7.3-rc1. If you are running Linux kernel 6.18.44 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2026-89639 actively exploited?

CVE-2026-89639 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2026-89639

High

In the Linux kernel, the following vulnerability has been resolved: cifs: use cifs_invalidate_cache() in cifs_do_truncate() for O_TRUNC cifs_do_truncate() is invoked from cifs_open() without i_rwsem, so it cannot use cifs_resize_file_locked() to perform a proper fscache cookie resize. Instead, add cifs_invalidate_cache() after cifs_setsize(). cifs_invalidate_cache() calls fscache_invalidate(), which works without holding i_rwsem: it unconditionally increments inval_counter and sets FSCACHE_COOKIE_NO_DATA_TO_READ, ensuring that stale cached data is not served once the cookie is later activated by fscache_use_cookie(). Truncation to zero leaves no valid cached data, making invalidation the correct semantic here.

Package Linux Kernel

Published 2026-09-11

Last modified 2026-09-13

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

High

Integrity

High

Availability

None

Vector string

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

Affected versions

Linux kernel versions 6.18.44, 6.12.105, 7.1.8, 7.2 and later are affected. Fixed in 6.18.50, 7.2.4, 7.3-rc1 and their respective stable series.

Affected from

≥ 6.18.44 ≥ 6.12.105 ≥ 7.1.8 ≥ 7.2

Fixed in

✓ 6.18.50 6.18.x ✓ 7.2.4 7.2.x ✓ 7.3-rc1

References

3 total

Details

CVE ID CVE-2026-89639

Severity High

CVSS score 7.1 / 10

CVSS version 3.1

Published 2026-09-11

Modified 2026-09-13

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2026-89639?

CVE-2026-89639 is a High severity Linux kernel vulnerability with a CVSS score of 7.1 out of 10 . It affects Linux kernel versions from 6.18.44 onward and has been patched in 6.18.50, 7.2.4 and 7.3-rc1. CVE-2026-89639 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2026-89639?

CVE-2026-89639 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:H/I:H/A:N.
Is there a patch available for CVE-2026-89639?

Yes. CVE-2026-89639 has been patched. Fixed versions include 6.18.50, 7.2.4 and 7.3-rc1. If you are running Linux kernel 6.18.44 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2026-89639 actively exploited?

No. CVE-2026-89639 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.