What is CVE-2026-64439?

CVE-2026-64439 is a Critical severity Linux kernel vulnerability with a CVSS score of 9.8 out of 10, classified as a Use After Free flaw (CWE-416), affecting Linux kernel versions from 6.15 onward and patched in 6.18.39, 7.1.4 and 7.2. CVE-2026-64439 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2026-64439?

CVE-2026-64439 has a CVSS score of 9.8 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:H/A:H.

Is there a patch available for CVE-2026-64439?

Yes, CVE-2026-64439 has been patched. Fixed versions include 6.18.39, 7.1.4 and 7.2. If you are running Linux kernel 6.15 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2026-64439 actively exploited?

CVE-2026-64439 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is Use After Free (CWE-416)?

The product references memory after it has been freed, which may cause it to crash, use unexpected values, or execute code. See MITRE CWE for full details: https://cwe.mitre.org/data/definitions/416.html

CVE-2026-64439

Critical

In the Linux kernel, the following vulnerability has been resolved: crypto: krb5 - filter out async aead implementations at alloc krb5_aead_encrypt(), krb5_aead_decrypt() in rfc3961_simplified.c and rfc8009_encrypt(), rfc8009_decrypt() in rfc8009_aes2.c set a NULL completion callback and treat any negative return from crypto_aead_{encrypt,decrypt}() as terminal, falling through to kfree_sensitive(buffer). When the encrypt_name resolves to an async AEAD instance the request returns -EINPROGRESS, the buffer is freed while the backend's worker still holds a pointer, and the worker dereferences the freed slab on completion. KASAN report under UML+SLUB with a synthetic async aead backend bound to krb5->encrypt_name: BUG: KASAN: slab-use-after-free in t5_stub_complete+0x7d/0xc7 The helpers were written synchronously, so filter the async instances out at allocation time instead of plumbing crypto_wait_req() through every call site. Reachable via net/rxrpc/rxgk.c, fs/afs/cm_security.c and net/ceph/crypto.c on systems with an async AEAD provider bound to the krb5 enctype name.

Package Linux Kernel

Published 2026-07-25

Last modified 2026-09-03

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

9.8

out of 10

Critical

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Vector string

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

Weakness type

CWE-416

CVE-2026-64439 is a Use After Free vulnerability

What is Use After Free?

The product references memory after it has been freed, which may cause it to crash, use unexpected values, or execute code. Learn more on MITRE CWE

Affected versions

Linux kernel versions 6.15 and later are affected. Fixed in 6.18.39, 7.1.4, 7.2 and their respective stable series.

Affected from

≥ 6.15

Fixed in

✓ 6.18.39 6.18.x ✓ 7.1.4 7.1.x ✓ 7.2

References

3 total

Kernel Git
https://git.kernel.org/stable/c/2b7bd6dccff14b8b632c5244f1fd506918077221

Patch
Kernel Git
https://git.kernel.org/stable/c/6c9dddeb582fde005360f4fe02c760d45ca05fb5

Patch
Kernel Git
https://git.kernel.org/stable/c/ef6feb77e2d91761427c5b773edc9c97e1b706ad

Patch

Details

CVE ID CVE-2026-64439

Severity Critical

CVSS score 9.8 / 10

CVSS version 3.1

Published 2026-07-25

Modified 2026-09-03

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2026-64439?

CVE-2026-64439 is a Critical severity Linux kernel vulnerability with a CVSS score of 9.8 out of 10 , classified as an Use After Free flaw (CWE-416) . It affects Linux kernel versions from 6.15 onward and has been patched in 6.18.39, 7.1.4 and 7.2. CVE-2026-64439 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2026-64439?

CVE-2026-64439 has a CVSS score of 9.8 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:H/A:H.
Is there a patch available for CVE-2026-64439?

Yes. CVE-2026-64439 has been patched. Fixed versions include 6.18.39, 7.1.4 and 7.2. If you are running Linux kernel 6.15 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2026-64439 actively exploited?

No. CVE-2026-64439 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.