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Fencer Vulns
critical 9.3

CVE-2026-64034 in the critical feed json

net: mana: Fix TOCTOU double-fetch of hwc_msg_id from DMA buffer

published 2026-07-19 3 mo ago modified 2026-10-19 20 d ago also EUVD-2026-45607

cvss
9.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 1%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

net: mana: Fix TOCTOU double-fetch of hwc_msg_id from DMA buffer

In mana_hwc_rx_event_handler(), resp->response.hwc_msg_id is read from DMA-coherent memory and bounds-checked, then mana_hwc_handle_resp() re-reads the same field from the same DMA buffer for test_bit() and pointer arithmetic.

DMA-coherent memory is mapped uncacheable on x86 and is shared, unencrypted, in Confidential VMs (SEV-SNP/TDX), so each load goes directly to host-visible memory. A H/W can modify the value between the check and the use, bypassing the bounds validation.

Fix this by reading hwc_msg_id exactly once using READ_ONCE() into a stack-local variable in mana_hwc_rx_event_handler(), and passing the validated value as a parameter to mana_hwc_handle_resp().

Patch / fix

  • Linux Linux 5.15.209, 6.1.175, 6.6.142, 6.12.92, 6.18.34, 7.0.11, 7.1
  • linux Debian 12 6.1.176-1
  • linux Debian 13 6.12.94-1
  • linux Debian 14 7.0.12-1

debian advisories DEBIAN-CVE-2026-64034

  • linux Ubuntu 22.04 LTS 5.15.0-186.196
  • linux Ubuntu 24.04 LTS 6.8.0-139.139
  • linux Ubuntu 26.04 LTS 7.0.0-28.28
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1112.119
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1064.67
  • linux-aws Ubuntu 26.04 LTS 7.0.0-1009.9
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1112.122
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1067.75

ubuntu advisories UBUNTU-CVE-2026-64034

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 10.2 6.12.0-211.62.1.el10_2
  • rv RHEL 10.2 6.12.0-211.62.1.el10_2
  • perf RHEL 10.2 6.12.0-211.62.1.el10_2
  • rtla RHEL 10.2 6.12.0-211.62.1.el10_2
  • libperf RHEL 10.2 6.12.0-211.62.1.el10_2
  • kernel-rt RHEL 10.2 6.12.0-211.62.1.el10_2
  • kernel-64k RHEL 10.2 6.12.0-211.62.1.el10_2
  • kernel-core RHEL 10.2 6.12.0-211.62.1.el10_2

red hat advisories RHSA-2026:75576RHSA-2026:72467RHSA-2026:72468RHSA-2026:66180

  • kernel-64kb SLE Module for Basesystem 15 SP7 6.4.0-150700.53.81.1
  • kernel-syms SLE Module for Development Tools 15 SP7 6.4.0-150700.53.81.1
  • kernel-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.53.81.1
  • kernel-source SLE Module for Development Tools 15 SP7, SLE Module for Basesystem 15 SP7 6.4.0-150700.53.81.1
  • kernel-default SLE Workstation Extension 15 SP7, SLE Module for Legacy 15 SP7, SLE Module for Basesystem 15 SP7 +2 more 6.4.0-150700.53.81.1
  • kernel-zfcpdump SLE Module for Basesystem 15 SP7 6.4.0-150700.53.81.1
  • kernel-obs-build SLE Module for Development Tools 15 SP7 6.4.0-150700.53.81.1
  • kernel-default-base SLE Module for Basesystem 15 SP7 6.4.0-150700.53.81.1.150700.17.45.1

suse advisories SUSE-SU-2026:4254-1SUSE-SU-2026:4369-1SUSE-SU-2026:4120-1SUSE-SU-2026:23481-1SUSE-SU-2026:23477-1SUSE-SU-2026:23529-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.37.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-azure openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.37.1

opensuse advisories openSUSE-SU-2026:21555-1

  • kernel AlmaLinux 10 6.12.0-211.62.1.el10_2
  • rv AlmaLinux 10 6.12.0-211.62.1.el10_2
  • perf AlmaLinux 10 6.12.0-211.62.1.el10_2
  • rtla AlmaLinux 10 6.12.0-211.62.1.el10_2
  • libperf AlmaLinux 10 6.12.0-211.62.1.el10_2
  • kernel-rt AlmaLinux 10 6.12.0-211.62.1.el10_2
  • kernel-64k AlmaLinux 10 6.12.0-211.62.1.el10_2
  • kernel-core AlmaLinux 10 6.12.0-211.62.1.el10_2

almalinux advisories ALSA-2026:75576ALSA-2026:72467ALSA-2026:72468ALSA-2026:66180

  • kernel Rocky Linux 10 6.12.0-211.62.1.el10_2
  • kernel-rt Rocky Linux 8 4.18.0-553.169.1.rt7.510.el8_10
  • kernel Rocky Linux 8 4.18.0-553.169.1.el8_10
  • kernel Rocky Linux 9 5.14.0-687.46.1.el9_8

rocky linux advisories RLSA-2026:75576RLSA-2026:72467RLSA-2026:72468RLSA-2026:66180

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-2026-64034 updated cvss 7.8

kernel: net: mana: Fix TOCTOU double-fetch of hwc_msg_id from DMA buffer

  • Red Hat Enterprise Linux 9 kernel-rt, kernel-rt-kvm, kernel-rt-core, kernel-rt-modules, kernel-rt-debug-kvm, kernel-rt-debug-core, +12 more
    affected: workaround, no fix available
  • Red Hat Enterprise Linux kernel-modules-internal 6.12.0-211.62.1.el10_2
    fixed: vendor fix RHSA-2026:75576
  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-687.46.1.el9_8, perf 5.14.0-687.46.1.el9_8, rtla 5.14.0-687.46.1.el9_8, python3-perf 5.14.0-687.46.1.el9_8, kernel-devel-matched 5.14.0-687.46.1.el9_8, kernel-64k-devel-matched 5.14.0-687.46.1.el9_8, +7 more
    fixed: vendor fix RHSA-2026:66180
  • Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-211.62.1.el10_2, perf 6.12.0-211.62.1.el10_2, rtla 6.12.0-211.62.1.el10_2, python3-perf 6.12.0-211.62.1.el10_2, kernel-devel-matched 6.12.0-211.62.1.el10_2, kernel-64k-devel-matched 6.12.0-211.62.1.el10_2, +7 more
    fixed: vendor fix RHSA-2026:75576
  • Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-553.169.1.el8_10, kernel 4.18.0-553.169.1.el8_10, bpftool 4.18.0-553.169.1.el8_10, kernel-core 4.18.0-553.169.1.el8_10, kernel-tools 4.18.0-553.169.1.el8_10, python3-perf 4.18.0-553.169.1.el8_10, +15 more
    fixed: vendor fix RHSA-2026:72468
  • Red Hat Enterprise Linux BaseOS (v. 9) kernel 5.14.0-687.46.1.el9_8, kernel-64k 5.14.0-687.46.1.el9_8, kernel-core 5.14.0-687.46.1.el9_8, kernel-tools 5.14.0-687.46.1.el9_8, kernel-modules 5.14.0-687.46.1.el9_8, kernel-64k-core 5.14.0-687.46.1.el9_8, +27 more
    fixed: vendor fix RHSA-2026:66180
  • Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-211.62.1.el10_2, kernel-64k 6.12.0-211.62.1.el10_2, kernel-core 6.12.0-211.62.1.el10_2, kernel-tools 6.12.0-211.62.1.el10_2, kernel-modules 6.12.0-211.62.1.el10_2, kernel-64k-core 6.12.0-211.62.1.el10_2, +28 more
    fixed: vendor fix RHSA-2026:75576
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) libperf 5.14.0-687.46.1.el9_8, kernel-debuginfo-common-s390x 5.14.0-687.46.1.el9_8, kernel-debuginfo-common-x86_64 5.14.0-687.46.1.el9_8, kernel-debuginfo-common-aarch64 5.14.0-687.46.1.el9_8, kernel-debuginfo-common-ppc64le 5.14.0-687.46.1.el9_8
    fixed: vendor fix RHSA-2026:66180
show 10 more
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-211.62.1.el10_2, kernel-debuginfo-common-s390x 6.12.0-211.62.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.62.1.el10_2, kernel-debuginfo-common-aarch64 6.12.0-211.62.1.el10_2, kernel-debuginfo-common-ppc64le 6.12.0-211.62.1.el10_2
    fixed: vendor fix RHSA-2026:75576
  • Red Hat Enterprise Linux CRB (v. 8) kernel-debuginfo-common-x86_64 4.18.0-553.169.1.el8_10, kernel-debuginfo-common-aarch64 4.18.0-553.169.1.el8_10, kernel-debuginfo-common-ppc64le 4.18.0-553.169.1.el8_10
    fixed: vendor fix RHSA-2026:72468
  • Red Hat Enterprise Linux Hidden (v. 10) kernel-modules-internal 6.12.0-211.62.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.62.1.el10_2
    fixed: vendor fix RHSA-2026:75576
  • Red Hat Enterprise Linux NFV (v. 8) kernel-rt 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-kvm 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-core 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-modules 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-debug-kvm 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-debug-core 4.18.0-553.169.1.rt7.510.el8_10, +4 more
    fixed: vendor fix RHSA-2026:72467
  • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt 5.14.0-687.46.1.el9_8, kernel-rt-64k 5.14.0-687.46.1.el9_8, kernel-rt-core 5.14.0-687.46.1.el9_8, kernel-rt-modules 5.14.0-687.46.1.el9_8, kernel-rt-64k-core 5.14.0-687.46.1.el9_8, kernel-rt-debug-core 5.14.0-687.46.1.el9_8, +14 more
    fixed: vendor fix RHSA-2026:66180
  • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-211.62.1.el10_2, kernel-rt-64k 6.12.0-211.62.1.el10_2, kernel-rt-core 6.12.0-211.62.1.el10_2, kernel-rt-modules 6.12.0-211.62.1.el10_2, kernel-rt-64k-core 6.12.0-211.62.1.el10_2, kernel-rt-debug-core 6.12.0-211.62.1.el10_2, +14 more
    fixed: vendor fix RHSA-2026:75576
  • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt 5.14.0-687.46.1.el9_8, kernel-rt-core 5.14.0-687.46.1.el9_8, kernel-rt-modules 5.14.0-687.46.1.el9_8, kernel-rt-debug-core 5.14.0-687.46.1.el9_8, kernel-rt-modules-core 5.14.0-687.46.1.el9_8, kernel-rt-debug-modules 5.14.0-687.46.1.el9_8, +4 more
    fixed: vendor fix RHSA-2026:66180
  • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-211.62.1.el10_2, kernel-rt-core 6.12.0-211.62.1.el10_2, kernel-rt-modules 6.12.0-211.62.1.el10_2, kernel-rt-debug-core 6.12.0-211.62.1.el10_2, kernel-rt-modules-core 6.12.0-211.62.1.el10_2, kernel-rt-debug-modules 6.12.0-211.62.1.el10_2, +4 more
    fixed: vendor fix RHSA-2026:75576
  • Red Hat Enterprise Linux RT (v. 8) kernel-rt 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-core 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-modules 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-debug-core 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-debug-modules 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-modules-extra 4.18.0-553.169.1.rt7.510.el8_10, +2 more
    fixed: vendor fix RHSA-2026:72467
  • 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
    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

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
23 d ago

Exploit prediction

0.11% chance of exploitation in the next 30 days, higher than 1% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 9.3 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Weakness
  • CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition
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.