--- id: CVE-2026-64531 title: |- 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 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: op… severity: high cvss: 7.8 cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H' published: '2026-07-27' updated: '2026-08-01' source: NVD sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-64531' references: - url: 'https://git.kernel.org/stable/c/1b41cbe05b184f8861712f0806cc0c4f5d8c6dfe' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/3f1f755366687d051174739fb99f7d560202f60b' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/ab855641241387db062a5e41d9ad6b8561542572' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/c66bd2626c2764f23764ff0f8277f44a9cfe8349' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/d573250d228401f707f4dbc09d11227a6215ee5f' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/dbd14f736be02cfe73049bd801af89becd1a0749' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/f1efff8858403191361a01269c6fe8dd7f55a385' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'http://www.openwall.com/lists/oss-security/2026/07/28/8' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'http://www.openwall.com/lists/oss-security/2026/07/31/17' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'http://www.openwall.com/lists/oss-security/2026/08/01/1' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'http://www.openwall.com/lists/oss-security/2026/08/01/3' label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64531.json - url: 'https://access.redhat.com/security/cve/CVE-2026-64531' - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2507402' - url: 'https://www.cve.org/CVERecord?id=CVE-2026-64531' - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-64531' - url: >- https://lore.kernel.org/linux-cve-announce/2026072732-CVE-2026-64531-e4ce@gregkh/T - url: 'https://access.redhat.com/errata/RHSA-2026:56786' - url: 'https://access.redhat.com/errata/RHSA-2026:56853' - url: 'https://access.redhat.com/errata/RHSA-2026:57483' - url: 'https://access.redhat.com/errata/RHSA-2026:57362' - url: 'https://access.redhat.com/errata/RHSA-2026:53330' - url: 'https://access.redhat.com/errata/RHSA-2026:51603' - url: 'https://access.redhat.com/errata/RHSA-2026:51746' - url: 'https://access.redhat.com/errata/RHSA-2026:53329' - url: 'https://access.redhat.com/errata/RHSA-2026:59143' - url: 'https://access.redhat.com/errata/RHSA-2026:59147' - url: 'https://access.redhat.com/errata/RHSA-2026:59145' - url: 'https://access.redhat.com/errata/RHSA-2026:59149' - url: 'https://access.redhat.com/errata/RHSA-2026:51604' tags: - nvd - exploit-available - csaf - vex - red-hat - cve.org epss: 0.0038 epssPercentile: 0.31825 ingestedAt: '2026-08-01T21:14:39.364Z' exploits: github: 4 githubRepos: - 'https://github.com/HackSpeak/CVE-2026-64531' - 'https://github.com/mahfuzreham/OVSwrap-CVE-2026-64531-Mitigation-Tool' - 'https://github.com/0xBlackash/CVE-2026-64531' checkedAt: '2026-10-27T19:07:21.809Z' exploitAvailable: true vendor: Red Hat product: Red Hat Enterprise Linux BaseOS E4S (v.9.4) affected: - enterprise_linux 9 - openshift_container_platform 4.14 - openshift_container_platform 4.16 - openshift_container_platform 4.18 - openshift_container_platform 4.22 - enterprise_linux_appstream_v_10 - enterprise_linux_appstream_e4s_v_9_2 - enterprise_linux_appstream_e4s_v_9_4 - enterprise_linux_appstream_v_9 - enterprise_linux_baseos_v_10 - enterprise_linux_baseos_e4s_v_9_2 - enterprise_linux_baseos_e4s_v_9_4 - enterprise_linux_baseos_v_9 - enterprise_linux_codeready_linux_builder_v_10 - enterprise_linux_codeready_linux_builder_v_9 - enterprise_linux_real_time_for_nfv_v_10 - enterprise_linux_real_time_for_nfv_e4s_v_9_2 - enterprise_linux_real_time_for_nfv_e4s_v_9_4 - enterprise_linux_real_time_for_nfv_v_9 - enterprise_linux_real_time_v_10 - enterprise_linux_real_time_e4s_v_9_2 - enterprise_linux_real_time_e4s_v_9_4 - enterprise_linux_real_time_v_9 patched: - openshift_container_platform 4.14 - openshift_container_platform 4.16 - openshift_container_platform 4.18 - openshift_container_platform 4.22 - enterprise_linux_appstream_v_10 - enterprise_linux_appstream_e4s_v_9_2 - enterprise_linux_appstream_e4s_v_9_4 - enterprise_linux_appstream_v_9 - enterprise_linux_baseos_v_10 - enterprise_linux_baseos_e4s_v_9_2 - enterprise_linux_baseos_e4s_v_9_4 - enterprise_linux_baseos_v_9 - enterprise_linux_codeready_linux_builder_v_10 - enterprise_linux_codeready_linux_builder_v_9 - enterprise_linux_real_time_for_nfv_v_10 - enterprise_linux_real_time_for_nfv_e4s_v_9_2 - enterprise_linux_real_time_for_nfv_e4s_v_9_4 - enterprise_linux_real_time_for_nfv_v_9 - enterprise_linux_real_time_v_10 - enterprise_linux_real_time_e4s_v_9_2 - enterprise_linux_real_time_e4s_v_9_4 - enterprise_linux_real_time_v_9 cwe: - CWE-130 ssvc: exploitation: none automatable: 'no' technicalImpact: total timestamp: '2026-10-16T15:41:46.689802Z' --- ## Overview 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. ## Remediation Refer to the linked advisories for vendor-supplied fixes and affected version ranges. ## Vendor advisories - **RHSA-2026:56786** · Red Hat · fixed in: Red Hat OpenShift Container Platform 4.14 · released 2026-08-31 · [advisory](https://access.redhat.com/errata/RHSA-2026:56786) - **RHSA-2026:56853** · Red Hat · fixed in: Red Hat OpenShift Container Platform 4.16 · released 2026-08-31 · [advisory](https://access.redhat.com/errata/RHSA-2026:56853) - **RHSA-2026:57483** · Red Hat · fixed in: Red Hat OpenShift Container Platform 4.18 · released 2026-08-26 · [advisory](https://access.redhat.com/errata/RHSA-2026:57483) - **RHSA-2026:57362** · Red Hat · fixed in: Red Hat OpenShift Container Platform 4.22 · released 2026-08-25 · [advisory](https://access.redhat.com/errata/RHSA-2026:57362) - **RHSA-2026:53330** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux BaseOS (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10), Red Hat Enterprise Linux Real Time for NFV (v. 10), Red Hat Enterprise Linux Real Time (v. 10) · released 2026-08-11 · [advisory](https://access.redhat.com/errata/RHSA-2026:53330) - **RHSA-2026:51603** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream E4S (v.9.2), Red Hat Enterprise Linux BaseOS E4S (v.9.2) · released 2026-08-07 · [advisory](https://access.redhat.com/errata/RHSA-2026:51603) - **RHSA-2026:51746** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream E4S (v.9.4), Red Hat Enterprise Linux BaseOS E4S (v.9.4), Red Hat Enterprise Linux Real Time for NFV E4S (v.9.4), Red Hat Enterprise Linux Real Time E4S (v.9.4) · released 2026-08-07 · [advisory](https://access.redhat.com/errata/RHSA-2026:51746) - **RHSA-2026:53329** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux BaseOS (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9), Red Hat Enterprise Linux Real Time for NFV (v. 9), Red Hat Enterprise Linux Real Time (v. 9) · released 2026-08-11 · [advisory](https://access.redhat.com/errata/RHSA-2026:53329) - **RHSA-2026:59143** · Red Hat · fixed in: Red Hat Enterprise Linux BaseOS (v. 10) · released 2026-08-24 · [advisory](https://access.redhat.com/errata/RHSA-2026:59143) - **RHSA-2026:59147** · Red Hat · fixed in: Red Hat Enterprise Linux BaseOS E4S (v.9.2) · released 2026-08-24 · [advisory](https://access.redhat.com/errata/RHSA-2026:59147) - **RHSA-2026:59145** · Red Hat · fixed in: Red Hat Enterprise Linux BaseOS E4S (v.9.4) · released 2026-08-24 · [advisory](https://access.redhat.com/errata/RHSA-2026:59145) - **Red Hat VEX** · Important · affected: Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 9 · updated 2026-10-05 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64531.json)