SB20260727127 - Use-after-free in Linux kernel krb5

Description

This security bulletin contains information about 1 vulnerability.

1) Use-after-free (CVE-ID: CVE-2026-64439)

CWE-ID: CWE-416 - Use After Free

CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear

The vulnerability allows a local user to cause a denial of service.

The vulnerability exists due to a use-after-free in krb5 AEAD encryption and decryption helpers when processing operations with an async AEAD implementation. A local user can trigger crypto operations using an async AEAD provider to cause a denial of service.

The issue is reachable via net/rxrpc/rxgk.c, fs/afs/cm_security.c, and net/ceph/crypto.c only on systems with an async AEAD provider bound to the krb5 enctype name.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/2b7bd6dccff14b8b632c5244f1fd506918077221
• https://git.kernel.org/stable/c/6c9dddeb582fde005360f4fe02c760d45ca05fb5
• https://git.kernel.org/stable/c/ef6feb77e2d91761427c5b773edc9c97e1b706ad