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Fencer Vulns
critical 9.8

CVE-2026-64037 in the critical feed json

wifi: iwlwifi: mld: fix TSO segmentation explosion when AMSDU is disabled

published 2026-07-19 3 mo ago modified 2026-10-19 20 d ago also EUVD-2026-45610

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:

wifi: iwlwifi: mld: fix TSO segmentation explosion when AMSDU is disabled

When the TLC notification disables AMSDU for a TID, the MLD driver sets max_tid_amsdu_len to the sentinel value 1. The TSO segmentation path in iwl_mld_tx_tso_segment() checks for zero but not for this sentinel, allowing it to reach the num_subframes calculation:

num_subframes = (max_tid_amsdu_len + pad) / (subf_len + pad) = (1 + 2) / (1534 + 2) = 0

This zero propagates to iwl_tx_tso_segment() which sets:

gso_size = num_subframes * mss = 0

Calling skb_gso_segment() with gso_size=0 creates over 32000 tiny segments from a single GSO skb. This floods the TX ring with ~1024 micro-frames (the rest are purged), creating a massive burst of TX completion events that can lead to memory corruption and a subsequent use-after-free in TCP's retransmit queue (refcount underflow in tcp_shifted_skb, NULL deref in tcp_rack_detect_loss).

The MVM driver is immune because it checks mvmsta->amsdu_enabled before reaching the num_subframes calculation. The MLD driver has no equivalent bitmap check and relies solely on max_tid_amsdu_len, which does not catch the sentinel value.

Fix this by detecting the sentinel value (max_tid_amsdu_len == 1) at the existing check and falling back to non-AMSDU TSO segmentation. Also add a WARN_ON_ONCE guard after the num_subframes division as defense-in-depth to catch any future code paths that produce zero through a different mechanism.

Patch / fix

  • Linux Linux 6.18.34, 7.0.11, 7.1
  • linux Debian 14 7.0.12-1

debian advisories DEBIAN-CVE-2026-64037

  • linux Ubuntu 26.04 LTS 7.0.0-28.28
  • linux-aws Ubuntu 26.04 LTS 7.0.0-1009.9
  • linux-gcp Ubuntu 26.04 LTS 7.0.0-1008.8
  • linux-gke Ubuntu 26.04 LTS 7.0.0-1003.4
  • linux-ibm Ubuntu 26.04 LTS 7.0.0-1010.10
  • linux-azure Ubuntu 26.04 LTS 7.0.0-1010.10
  • linux-raspi Ubuntu 26.04 LTS 7.0.0-1015.15
  • linux-riscv Ubuntu 26.04 LTS 7.0.0-28.28.1

ubuntu advisories UBUNTU-CVE-2026-64037

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 5.14.0-687.47.1.el9_8
  • rv RHEL 9 5.14.0-687.47.1.el9_8
  • perf RHEL 9 5.14.0-687.47.1.el9_8
  • rtla RHEL 9 5.14.0-687.47.1.el9_8
  • libperf RHEL 9 5.14.0-687.47.1.el9_8
  • kernel-rt RHEL 9 5.14.0-687.47.1.el9_8
  • kernel-64k RHEL 9 5.14.0-687.47.1.el9_8
  • kernel-core RHEL 9 5.14.0-687.47.1.el9_8

red hat advisories RHSA-2026:67150RHSA-2026:65334

  • kernel AlmaLinux 9 5.14.0-687.47.1.el9_8
  • rv AlmaLinux 9 5.14.0-687.47.1.el9_8
  • perf AlmaLinux 9 5.14.0-687.47.1.el9_8
  • rtla AlmaLinux 9 5.14.0-687.47.1.el9_8
  • libperf AlmaLinux 9 5.14.0-687.47.1.el9_8
  • kernel-rt AlmaLinux 9 5.14.0-687.47.1.el9_8
  • kernel-64k AlmaLinux 9 5.14.0-687.47.1.el9_8
  • kernel-core AlmaLinux 9 5.14.0-687.47.1.el9_8

almalinux advisories ALSA-2026:67150ALSA-2026:65334

  • kernel Rocky Linux 9 5.14.0-687.47.1.el9_8
  • kernel Rocky Linux 10 6.12.0-211.53.1.el10_2

rocky linux advisories RLSA-2026:67150RLSA-2026:65334

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-2026-64037 updated cvss 7.0

kernel: wifi: iwlwifi: mld: fix TSO segmentation explosion when AMSDU is disabled

  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-687.47.1.el9_8, perf 5.14.0-687.47.1.el9_8, rtla 5.14.0-687.47.1.el9_8, python3-perf 5.14.0-687.47.1.el9_8, kernel-devel-matched 5.14.0-687.47.1.el9_8, kernel-64k-devel-matched 5.14.0-687.47.1.el9_8, +7 more
    fixed: vendor fix RHSA-2026:67150
  • Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-211.53.1.el10_2, perf 6.12.0-211.53.1.el10_2, rtla 6.12.0-211.53.1.el10_2, python3-perf 6.12.0-211.53.1.el10_2, kernel-devel-matched 6.12.0-211.53.1.el10_2, kernel-64k-devel-matched 6.12.0-211.53.1.el10_2, +7 more
    fixed: vendor fix RHSA-2026:65334
  • Red Hat Enterprise Linux BaseOS (v. 9) kernel 5.14.0-687.47.1.el9_8, kernel-64k 5.14.0-687.47.1.el9_8, kernel-core 5.14.0-687.47.1.el9_8, kernel-tools 5.14.0-687.47.1.el9_8, kernel-modules 5.14.0-687.47.1.el9_8, kernel-64k-core 5.14.0-687.47.1.el9_8, +27 more
    fixed: vendor fix RHSA-2026:67150
  • Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-211.53.1.el10_2, kernel-64k 6.12.0-211.53.1.el10_2, kernel-core 6.12.0-211.53.1.el10_2, kernel-tools 6.12.0-211.53.1.el10_2, kernel-modules 6.12.0-211.53.1.el10_2, kernel-64k-core 6.12.0-211.53.1.el10_2, +28 more
    fixed: vendor fix RHSA-2026:65334
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) libperf 5.14.0-687.47.1.el9_8, kernel-debuginfo-common-s390x 5.14.0-687.47.1.el9_8, kernel-debuginfo-common-x86_64 5.14.0-687.47.1.el9_8, kernel-debuginfo-common-aarch64 5.14.0-687.47.1.el9_8, kernel-debuginfo-common-ppc64le 5.14.0-687.47.1.el9_8
    fixed: vendor fix RHSA-2026:67150
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-211.53.1.el10_2, kernel-debuginfo-common-s390x 6.12.0-211.53.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.53.1.el10_2, kernel-debuginfo-common-aarch64 6.12.0-211.53.1.el10_2, kernel-debuginfo-common-ppc64le 6.12.0-211.53.1.el10_2
    fixed: vendor fix RHSA-2026:65334
  • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt 5.14.0-687.47.1.el9_8, kernel-rt-64k 5.14.0-687.47.1.el9_8, kernel-rt-core 5.14.0-687.47.1.el9_8, kernel-rt-modules 5.14.0-687.47.1.el9_8, kernel-rt-64k-core 5.14.0-687.47.1.el9_8, kernel-rt-debug-core 5.14.0-687.47.1.el9_8, +14 more
    fixed: vendor fix RHSA-2026:67150
  • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-211.53.1.el10_2, kernel-rt-64k 6.12.0-211.53.1.el10_2, kernel-rt-core 6.12.0-211.53.1.el10_2, kernel-rt-modules 6.12.0-211.53.1.el10_2, kernel-rt-64k-core 6.12.0-211.53.1.el10_2, kernel-rt-debug-core 6.12.0-211.53.1.el10_2, +14 more
    fixed: vendor fix RHSA-2026:65334
show 3 more
  • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt 5.14.0-687.47.1.el9_8, kernel-rt-core 5.14.0-687.47.1.el9_8, kernel-rt-modules 5.14.0-687.47.1.el9_8, kernel-rt-debug-core 5.14.0-687.47.1.el9_8, kernel-rt-modules-core 5.14.0-687.47.1.el9_8, kernel-rt-debug-modules 5.14.0-687.47.1.el9_8, +4 more
    fixed: vendor fix RHSA-2026:67150
  • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-211.53.1.el10_2, kernel-rt-core 6.12.0-211.53.1.el10_2, kernel-rt-modules 6.12.0-211.53.1.el10_2, kernel-rt-debug-core 6.12.0-211.53.1.el10_2, kernel-rt-modules-core 6.12.0-211.53.1.el10_2, kernel-rt-debug-modules 6.12.0-211.53.1.el10_2, +4 more
    fixed: vendor fix RHSA-2026:65334
  • 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-kvm, kernel-rt-core, kernel-rt-modules, kernel-rt-debug-kvm, kernel-rt-debug-core, +12 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
yes
Technical impact
total
Assessed
23 d ago

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
  • CWE-20 Improper Input Validation
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.