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Fencer Vulns
critical 9.8

CVE-2026-64439 in the critical feed json

crypto: krb5 - filter out async aead implementations at alloc

published 2026-07-25 3 mo ago modified 2026-10-24 15 d ago also EUVD-2026-48783

cvss
9.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 37%
public exploits
0
none known

Summary

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.

Patch / fix

  • Linux Linux 6.18.39, 7.1.4, 7.2
  • linux Debian 14 7.1.4-1

debian advisories DEBIAN-CVE-2026-64439

  • linux Ubuntu 26.04 LTS 7.0.0-31.31
  • linux-aws Ubuntu 26.04 LTS 7.0.0-1012.12
  • linux-gcp Ubuntu 26.04 LTS 7.0.0-1011.11
  • linux-gke Ubuntu 26.04 LTS 7.0.0-1006.7
  • linux-ibm Ubuntu 26.04 LTS 7.0.0-1013.13
  • linux-azure Ubuntu 26.04 LTS 7.0.0-1014.14
  • linux-raspi Ubuntu 26.04 LTS 7.0.0-1019.19
  • linux-riscv Ubuntu 26.04 LTS 7.0.0-31.31.1

ubuntu advisories UBUNTU-CVE-2026-64439

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel RHEL 9.4 E4S 5.14.0-427.136.1.el9_4
  • rv RHEL 9.4 E4S 5.14.0-427.136.1.el9_4
  • perf RHEL 9.4 E4S 5.14.0-427.136.1.el9_4
  • rtla RHEL 9.4 E4S 5.14.0-427.136.1.el9_4
  • bpftool RHEL 9.4 E4S 7.3.0-427.136.1.el9_4
  • kernel-rt RHEL 9.4 E4S 5.14.0-427.136.1.el9_4
  • kernel-64k RHEL 9.4 E4S 5.14.0-427.136.1.el9_4
  • kernel-core RHEL 9.4 E4S 5.14.0-427.136.1.el9_4

red hat advisories RHSA-2026:36767

  • kernel-source openSUSE Tumbleweed 7.1.7-1.1

opensuse advisories openSUSE-SU-2026:11476-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-64439 updated cvss 8.8

kernel: crypto: krb5 - filter out async aead implementations at alloc

  • Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +82 more
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Enterprise Linux 10 kernel
    affected: workaround, no fix available
  • Red Hat Enterprise Linux AppStream E4S (v.9.4) rv 5.14.0-427.136.1.el9_4, perf 5.14.0-427.136.1.el9_4, rtla 5.14.0-427.136.1.el9_4, kernel-devel-matched 5.14.0-427.136.1.el9_4, kernel-64k-devel-matched 5.14.0-427.136.1.el9_4, kernel-debug-devel-matched 5.14.0-427.136.1.el9_4, +6 more Red Hat Enterprise Linux BaseOS E4S (v.9.4) bpftool 7.3.0-427.136.1.el9_4, kernel 5.14.0-427.136.1.el9_4, kernel-64k 5.14.0-427.136.1.el9_4, kernel-core 5.14.0-427.136.1.el9_4, kernel-tools 5.14.0-427.136.1.el9_4, python3-perf 5.14.0-427.136.1.el9_4, +28 more Red Hat Enterprise Linux Real Time E4S (v.9.4) kernel-rt 5.14.0-427.136.1.el9_4, kernel-rt-core 5.14.0-427.136.1.el9_4, kernel-rt-modules 5.14.0-427.136.1.el9_4, kernel-rt-debug-core 5.14.0-427.136.1.el9_4, kernel-rt-modules-core 5.14.0-427.136.1.el9_4, kernel-rt-debug-modules 5.14.0-427.136.1.el9_4, +4 more Red Hat Enterprise Linux Real Time for NFV E4S (v.9.4) kernel-rt 5.14.0-427.136.1.el9_4, kernel-rt-kvm 5.14.0-427.136.1.el9_4, kernel-rt-core 5.14.0-427.136.1.el9_4, kernel-rt-modules 5.14.0-427.136.1.el9_4, kernel-rt-debug-kvm 5.14.0-427.136.1.el9_4, kernel-rt-debug-core 5.14.0-427.136.1.el9_4, +6 more
    fixed: vendor fix RHSA-2026:36767
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 kernel-rt, kernel-rt-selftests-internal
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.43% chance of exploitation in the next 30 days, higher than 37% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Weakness
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.