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Fencer Vulns
high 7.8

CVE-2026-64531 json

net: openvswitch: reject oversized nested action attrs

published 2026-07-27 3 mo ago modified 2026-11-03 5 d ago also EUVD-2026-49109

cvss
7.8
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 32%
public exploits
0
none known

Summary

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

net: openvswitch: reject oversized nested action attrs

Open vSwitch stores generated flow actions as nlattrs, whose nla_len field is u16. Commit a1e64addf3ff ("net: openvswitch: remove misbehaving actions length check") allowed the total sw_flow_actions stream to grow beyond 64 KiB, which is valid, but also removed the last guard preventing a generated nested action attribute from exceeding U16_MAX.

An oversized generated container can thus be closed with a truncated nla_len. A later dump or teardown then walks a structurally different stream than the one that was validated. In particular, an oversized nested CLONE/CT action may cause subsequent bytes in the generated stream to be interpreted as independent actions.

Keep the larger total-action-stream behavior, but make nested action close reject generated containers that do not fit in nla_len, and return the error through all callers. For recursive SAMPLE, CLONE, DEC_TTL, and CHECK_PKT_LEN builders, trim resource-owning action-list tails in reverse construction order before discarding failed wrappers, so resources copied into the rejected tails are released before the wrappers are removed.

Most failed outer wrappers are discarded by truncating actions_len after child resources have been released. CHECK_PKT_LEN also trims its parent after branch resources are gone. SET/TUNNEL close failures unwind their known tun_dst ownership directly, and SET_TO_MASKED has no external ownership and truncates on close failure.

Patch / fix

  • Linux Linux 5.15.212, 6.1.178, 6.6.145, 6.12.97, 6.14, 6.18.40, 7.1.5, 7.2
  • linux Debian 12 6.1.180-1
  • linux Debian 13 6.12.100-1
  • linux Debian 14 7.1.5-1
  • linux-6.12 Debian 12 6.12.100-1~deb12u1

debian advisories DEBIAN-CVE-2026-64531

  • linux Ubuntu 22.04 LTS 5.15.0-190.200
  • linux Ubuntu 24.04 LTS 6.8.0-138.138
  • linux Ubuntu 26.04 LTS 7.0.0-30.30
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1114.121
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1063.66
  • linux-aws Ubuntu 26.04 LTS 7.0.0-1011.11
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1114.124
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1066.74

ubuntu advisories UBUNTU-CVE-2026-64531

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

  • kpatch-patch-5_14_0-687_10_1 RHEL 9 1-7.el9_8
  • kpatch-patch-6_12_0-211_16_1 RHEL 10.2 1-7.el10_2
  • kernel RHEL 9 5.14.0-687.38.1.el9_8
  • rv RHEL 9 5.14.0-687.38.1.el9_8
  • perf RHEL 9 5.14.0-687.38.1.el9_8
  • rtla RHEL 9 5.14.0-687.38.1.el9_8
  • libperf RHEL 9 5.14.0-687.38.1.el9_8
  • kernel-rt RHEL 9 5.14.0-687.38.1.el9_8

red hat advisories RHSA-2026:59149RHSA-2026:59147RHSA-2026:59145RHSA-2026:59143RHSA-2026:53329RHSA-2026:53330

  • kernel-source openSUSE Tumbleweed 7.1.7-1.1

opensuse advisories openSUSE-SU-2026:11476-1

  • kernel AlmaLinux 9 5.14.0-687.38.1.el9_8
  • rv AlmaLinux 9 5.14.0-687.38.1.el9_8
  • perf AlmaLinux 9 5.14.0-687.38.1.el9_8
  • rtla AlmaLinux 9 5.14.0-687.38.1.el9_8
  • libperf AlmaLinux 9 5.14.0-687.38.1.el9_8
  • kernel-rt AlmaLinux 9 5.14.0-687.38.1.el9_8
  • kernel-64k AlmaLinux 9 5.14.0-687.38.1.el9_8
  • kernel-core AlmaLinux 9 5.14.0-687.38.1.el9_8

almalinux advisories ALSA-2026:53329ALSA-2026:53330

  • kernel Rocky Linux 10 6.12.0-211.46.1.el10_2
  • kernel Rocky Linux 9 5.14.0-687.38.1.el9_8

rocky linux advisories RLSA-2026:53330RLSA-2026:53329

  • kernel Azure Linux 3.0 6.6.145.2-1

azure linux advisories AZL-93965

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

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-2026-64531 updated cvss 7.8

kernel: net: openvswitch: reject oversized nested action attrs

  • Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9
    affected: workaround, no fix available
  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-687.38.1.el9_8, perf 5.14.0-687.38.1.el9_8, rtla 5.14.0-687.38.1.el9_8, python3-perf 5.14.0-687.38.1.el9_8, kernel-devel-matched 5.14.0-687.38.1.el9_8, kernel-64k-devel-matched 5.14.0-687.38.1.el9_8, +7 more
    fixed: vendor fix RHSA-2026:53329
  • Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-211.46.1.el10_2, perf 6.12.0-211.46.1.el10_2, rtla 6.12.0-211.46.1.el10_2, python3-perf 6.12.0-211.46.1.el10_2, kernel-devel-matched 6.12.0-211.46.1.el10_2, kernel-64k-devel-matched 6.12.0-211.46.1.el10_2, +7 more
    fixed: vendor fix RHSA-2026:53330
  • Red Hat Enterprise Linux AppStream E4S (v.9.2) perf 5.14.0-284.186.1.el9_2, rtla 5.14.0-284.186.1.el9_2, kernel-devel-matched 5.14.0-284.186.1.el9_2, kernel-64k-devel-matched 5.14.0-284.186.1.el9_2, kernel-debug-devel-matched 5.14.0-284.186.1.el9_2, kernel-debuginfo-common-s390x 5.14.0-284.186.1.el9_2, +5 more
    fixed: vendor fix RHSA-2026:51603
  • Red Hat Enterprise Linux AppStream E4S (v.9.4) rv 5.14.0-427.143.1.el9_4, perf 5.14.0-427.143.1.el9_4, rtla 5.14.0-427.143.1.el9_4, kernel-devel-matched 5.14.0-427.143.1.el9_4, kernel-64k-devel-matched 5.14.0-427.143.1.el9_4, kernel-debug-devel-matched 5.14.0-427.143.1.el9_4, +6 more
    fixed: vendor fix RHSA-2026:51746
  • Red Hat Enterprise Linux BaseOS (v. 9) kernel 5.14.0-687.38.1.el9_8, kernel-64k 5.14.0-687.38.1.el9_8, kernel-core 5.14.0-687.38.1.el9_8, kernel-tools 5.14.0-687.38.1.el9_8, kernel-modules 5.14.0-687.38.1.el9_8, kernel-64k-core 5.14.0-687.38.1.el9_8, +28 more
    fixed: vendor fix RHSA-2026:53329
  • Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-211.46.1.el10_2, kernel-64k 6.12.0-211.46.1.el10_2, kernel-core 6.12.0-211.46.1.el10_2, kernel-tools 6.12.0-211.46.1.el10_2, kernel-modules 6.12.0-211.46.1.el10_2, kernel-64k-core 6.12.0-211.46.1.el10_2, +29 more
    fixed: vendor fix RHSA-2026:53330
  • Red Hat Enterprise Linux BaseOS E4S (v.9.2) bpftool 7.0.0-284.186.1.el9_2, kernel 5.14.0-284.186.1.el9_2, kernel-64k 5.14.0-284.186.1.el9_2, kernel-core 5.14.0-284.186.1.el9_2, kernel-tools 5.14.0-284.186.1.el9_2, python3-perf 5.14.0-284.186.1.el9_2, +33 more
    fixed: vendor fix RHSA-2026:51603
show 16 more
  • Red Hat Enterprise Linux BaseOS E4S (v.9.4) bpftool 7.3.0-427.143.1.el9_4, kernel 5.14.0-427.143.1.el9_4, kernel-64k 5.14.0-427.143.1.el9_4, kernel-core 5.14.0-427.143.1.el9_4, kernel-tools 5.14.0-427.143.1.el9_4, python3-perf 5.14.0-427.143.1.el9_4, +33 more
    fixed: vendor fix RHSA-2026:51746
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) libperf 5.14.0-687.38.1.el9_8, kernel-debuginfo-common-s390x 5.14.0-687.38.1.el9_8, kernel-debuginfo-common-x86_64 5.14.0-687.38.1.el9_8, kernel-debuginfo-common-aarch64 5.14.0-687.38.1.el9_8, kernel-debuginfo-common-ppc64le 5.14.0-687.38.1.el9_8
    fixed: vendor fix RHSA-2026:53329
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-211.46.1.el10_2, kernel-debuginfo-common-s390x 6.12.0-211.46.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.46.1.el10_2, kernel-debuginfo-common-aarch64 6.12.0-211.46.1.el10_2, kernel-debuginfo-common-ppc64le 6.12.0-211.46.1.el10_2
    fixed: vendor fix RHSA-2026:53330
  • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt 5.14.0-687.38.1.el9_8, kernel-rt-64k 5.14.0-687.38.1.el9_8, kernel-rt-core 5.14.0-687.38.1.el9_8, kernel-rt-modules 5.14.0-687.38.1.el9_8, kernel-rt-64k-core 5.14.0-687.38.1.el9_8, kernel-rt-debug-core 5.14.0-687.38.1.el9_8, +14 more
    fixed: vendor fix RHSA-2026:53329
  • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-211.46.1.el10_2, kernel-rt-64k 6.12.0-211.46.1.el10_2, kernel-rt-core 6.12.0-211.46.1.el10_2, kernel-rt-modules 6.12.0-211.46.1.el10_2, kernel-rt-64k-core 6.12.0-211.46.1.el10_2, kernel-rt-debug-core 6.12.0-211.46.1.el10_2, +14 more
    fixed: vendor fix RHSA-2026:53330
  • Red Hat Enterprise Linux Real Time E4S (v.9.2) kernel-rt 5.14.0-284.186.1.rt14.471.el9_2, kernel-rt-core 5.14.0-284.186.1.rt14.471.el9_2, kernel-rt-modules 5.14.0-284.186.1.rt14.471.el9_2, kernel-rt-debug-core 5.14.0-284.186.1.rt14.471.el9_2, kernel-rt-modules-core 5.14.0-284.186.1.rt14.471.el9_2, kernel-rt-debug-modules 5.14.0-284.186.1.rt14.471.el9_2, +4 more
    fixed: vendor fix RHSA-2026:51604
  • Red Hat Enterprise Linux Real Time E4S (v.9.4) kernel-rt 5.14.0-427.143.1.el9_4, kernel-rt-core 5.14.0-427.143.1.el9_4, kernel-rt-modules 5.14.0-427.143.1.el9_4, kernel-rt-debug-core 5.14.0-427.143.1.el9_4, kernel-rt-modules-core 5.14.0-427.143.1.el9_4, kernel-rt-debug-modules 5.14.0-427.143.1.el9_4, +4 more
    fixed: vendor fix RHSA-2026:51746
  • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt 5.14.0-687.38.1.el9_8, kernel-rt-core 5.14.0-687.38.1.el9_8, kernel-rt-modules 5.14.0-687.38.1.el9_8, kernel-rt-debug-core 5.14.0-687.38.1.el9_8, kernel-rt-modules-core 5.14.0-687.38.1.el9_8, kernel-rt-debug-modules 5.14.0-687.38.1.el9_8, +4 more
    fixed: vendor fix RHSA-2026:53329
  • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-211.46.1.el10_2, kernel-rt-core 6.12.0-211.46.1.el10_2, kernel-rt-modules 6.12.0-211.46.1.el10_2, kernel-rt-debug-core 6.12.0-211.46.1.el10_2, kernel-rt-modules-core 6.12.0-211.46.1.el10_2, kernel-rt-debug-modules 6.12.0-211.46.1.el10_2, +4 more
    fixed: vendor fix RHSA-2026:53330
  • Red Hat Enterprise Linux Real Time for NFV E4S (v.9.2) kernel-rt 5.14.0-284.186.1.rt14.471.el9_2, kernel-rt-kvm 5.14.0-284.186.1.rt14.471.el9_2, kernel-rt-core 5.14.0-284.186.1.rt14.471.el9_2, kernel-rt-modules 5.14.0-284.186.1.rt14.471.el9_2, kernel-rt-debug-kvm 5.14.0-284.186.1.rt14.471.el9_2, kernel-rt-debug-core 5.14.0-284.186.1.rt14.471.el9_2, +6 more
    fixed: vendor fix RHSA-2026:51604
  • Red Hat Enterprise Linux Real Time for NFV E4S (v.9.4) kernel-rt 5.14.0-427.143.1.el9_4, kernel-rt-kvm 5.14.0-427.143.1.el9_4, kernel-rt-core 5.14.0-427.143.1.el9_4, kernel-rt-modules 5.14.0-427.143.1.el9_4, kernel-rt-debug-kvm 5.14.0-427.143.1.el9_4, kernel-rt-debug-core 5.14.0-427.143.1.el9_4, +6 more
    fixed: vendor fix RHSA-2026:51746
  • Red Hat OpenShift Container Platform 4.14 rhcos 414.92.202608172040
    fixed: vendor fix RHSA-2026:56786
  • Red Hat OpenShift Container Platform 4.16 rhcos 416.94.202608150307
    fixed: vendor fix RHSA-2026:56853
  • Red Hat OpenShift Container Platform 4.18 rhcos 418.94.202608142238
    fixed: vendor fix RHSA-2026:57483
  • Red Hat OpenShift Container Platform 4.22 rhcos 4.22.9.8.202608191915
    fixed: vendor fix RHSA-2026:57362
  • 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 OpenShift Container Platform 4 openshift/ose-rhel-coreos-8
    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

0.38% chance of exploitation in the next 30 days, higher than 32% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Weakness
  • CWE-190 Integer Overflow or Wraparound
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.