CVE-2026-64439: In the Linux kernel, the following vulnerability has been resolved: crypto: krb5 - filter out async aead impl

Q: How do I fix CVE-2026-64439?

linux kernel: upgrade to 6.18.39, 7.1.4. Exact commands for each OS are on this page.

Q: Is CVE-2026-64439 being exploited?

CVE-2026-64439 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-64439 affect?

CVE-2026-64439 affects linux kernel. Severity is critical (CVSS 9.8). 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

Q: How urgent is CVE-2026-64439?

Priority 57/100. Critical severity; Remotely exploitable, no login, no user action; On your watchlist

This month

CRITICAL 9.8REMOTEWATCHLISTUPGRADE

CVE-2026-64439 is a critical-severity flaw (CVSS 9.8) affecting linux kernel. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 a

Why this priority

Critical severity
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.6% (top 50%)
CISA exploited list	No
Weakness	CWE-416
Published	2026-07-25
Last modified	2026-10-24

Publisher (CNA): kernel.org · Vendor: linux

Last updated 2026-10-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-25 10:17 UTCPublished CVE record published
2026-10-24 13:10 UTCUpdated Record last modified

linux linux kernel UPGRADE

Affected: >= 6.15 and < 6.18.39 · >= 6.19 and < 7.1.4

Fixed in: 6.18.39, 7.1.4

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Exact fixes by distribution

Fedora 46 · gnome-shell-extension-tiling-assistant · FIXED · 56-1.fc46 · FEDORA-2026-ebf66a5321 · source

sudo dnf upgrade --advisory=FEDORA-2026-ebf66a5321

Ubuntu 20.04 · linux · NOT AFFECTED

Ubuntu 22.04 · linux · NOT AFFECTED

Ubuntu 24.04 · linux · NOT AFFECTED

Ubuntu 20.04 · linux-hwe-5.15 · NOT AFFECTED

Ubuntu 22.04 · linux-hwe-6.8 · NOT AFFECTED

Debian 12 · linux · NOT AFFECTED

Debian 13 · linux · NOT AFFECTED

RHEL 9.4 Update Services for SAP Solutions · kernel · FIXED · kernel-5.14.0-427.136.1.el9_4

sudo dnf upgrade --advisory=RHSA-2026:36767 rpm -q kernel

RHEL 10 · kernel · NO FIX YET

RHEL 6 · kernel · NOT AFFECTED

RHEL 7 · kernel · NOT AFFECTED

RHEL 7 · kernel-rt · NOT AFFECTED

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-64439?

linux kernel: upgrade to 6.18.39, 7.1.4. Exact commands for each OS are on this page.

Is CVE-2026-64439 being exploited?

CVE-2026-64439 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-64439 affect?

CVE-2026-64439 affects linux kernel. Severity is critical (CVSS 9.8). 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

How urgent is CVE-2026-64439?

Priority 57/100. Critical severity; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Linux kernel vulnerabilities

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References

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