--- id: CVE-2026-45856 title: >- kernel: RDMA/uverbs: Validate wqe_size before using it in ib_uverbs_post_send (CVE-2026-45856) summary: >- A flaw was found in the Linux kernel's Remote Direct Memory Access (RDMA) subsystem, specifically within the `ib_uverbs_post_send` function. A local user can exploit this vulnerability by providing an invalid work queue element size (`wqe_… severity: high cvss: 7 cvssVector: 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H' cvssSource: vendor cwe: CWE-1284 vendor: Red Hat product: Red Hat Enterprise Linux BaseOS (v. 10) affected: - enterprise_linux 6 - enterprise_linux 7 - enterprise_linux 9 - 10base_smtv - enterprise_linux_appstream_v_10 - enterprise_linux_appstream_v_9 - enterprise_linux_baseos_v_10 - enterprise_linux_baseos_v_8 - enterprise_linux_baseos_v_9 - enterprise_linux_codeready_linux_builder_v_10 - enterprise_linux_crb_v_8 - enterprise_linux_codeready_linux_builder_v_9 - enterprise_linux_hidden_v_10 - enterprise_linux_real_time_for_nfv_v_10 - enterprise_linux_nfv_v_8 - enterprise_linux_real_time_for_nfv_v_9 - enterprise_linux_real_time_v_10 - enterprise_linux_rt_v_8 - enterprise_linux_real_time_v_9 patched: - 10base_smtv - enterprise_linux_appstream_v_10 - enterprise_linux_appstream_v_9 - enterprise_linux_baseos_v_10 - enterprise_linux_baseos_v_8 - enterprise_linux_baseos_v_9 - enterprise_linux_codeready_linux_builder_v_10 - enterprise_linux_crb_v_8 - enterprise_linux_codeready_linux_builder_v_9 - enterprise_linux_hidden_v_10 - enterprise_linux_real_time_for_nfv_v_10 - enterprise_linux_nfv_v_8 - enterprise_linux_real_time_for_nfv_v_9 - enterprise_linux_real_time_v_10 - enterprise_linux_rt_v_8 - enterprise_linux_real_time_v_9 published: '2026-05-27' updated: '2026-10-26' sourceUpdated: '2026-10-26T09:37:00+00:00' source: CSAF sourceUrl: 'https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-45856.json' references: - url: >- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-45856.json - url: 'https://access.redhat.com/security/cve/CVE-2026-45856' - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2482129' - url: 'https://www.cve.org/CVERecord?id=CVE-2026-45856' - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-45856' - url: >- https://lore.kernel.org/linux-cve-announce/2026052709-CVE-2026-45856-92b9@gregkh/T - url: 'https://access.redhat.com/errata/RHSA-2026:76738' - url: 'https://access.redhat.com/errata/RHSA-2026:74438' - url: 'https://access.redhat.com/errata/RHSA-2026:75747' - url: 'https://access.redhat.com/errata/RHSA-2026:75746' - url: 'https://git.kernel.org/stable/c/9c15ec4cd4e7f57c6bbcb4e73e99290f150dd2a7' - url: 'https://git.kernel.org/stable/c/9b5ac1c15334d46c0dbd49d64a2257b929500163' - url: 'https://git.kernel.org/stable/c/01c9b152647dc70dc06a4a2eff86ebb3b3c76075' - url: 'https://git.kernel.org/stable/c/bf1feed1a7886af945f92890493aefd2b5c9928a' - url: 'https://git.kernel.org/stable/c/d533425ac1f2925b4fc3e4ed9b9d72362cb23475' - url: 'https://git.kernel.org/stable/c/bf4454da8b1e712714628c0a0d6e7845bb40790a' - url: 'https://git.kernel.org/stable/c/bef70ff9841990658610512b4a18e4a88c9b4df6' - url: 'https://git.kernel.org/stable/c/1956f0a74ccf5dc9c3ef717f2985c3ed3400aab0' tags: - csaf - vex - red-hat - cve.org epss: 0.00187 epssPercentile: 0.08249 ssvc: exploitation: none automatable: 'no' technicalImpact: partial timestamp: '2026-10-16T15:18:02.441726Z' scores: vendor: 7 cna: 7.1 ingestedAt: '2026-10-16T17:24:46.699Z' --- ## Overview A flaw was found in the Linux kernel's Remote Direct Memory Access (RDMA) subsystem, specifically within the `ib_uverbs_post_send` function. A local user can exploit this vulnerability by providing an invalid work queue element size (`wqe_size`) from userspace without proper validation. This can lead to an out-of-bounds read from kernel heap memory, potentially disclosing sensitive kernel information to the user. Additionally, an excessively large `wqe_size` could trigger a kernel warning. ## Vendor advisories - **RHSA-2026:76738** · Red Hat · fixed in: 10Base-SMTV, 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 Hidden (v. 10), Red Hat Enterprise Linux Real Time for NFV (v. 10), … · released 2026-10-08 · [advisory](https://access.redhat.com/errata/RHSA-2026:76738) - **RHSA-2026:74438** · 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 2026-10-02 · [advisory](https://access.redhat.com/errata/RHSA-2026:74438) - **RHSA-2026:75747** · Red Hat · fixed in: Red Hat Enterprise Linux BaseOS (v. 8), Red Hat Enterprise Linux CRB (v. 8) · released 2026-10-05 · [advisory](https://access.redhat.com/errata/RHSA-2026:75747) - **RHSA-2026:75746** · Red Hat · fixed in: Red Hat Enterprise Linux NFV (v. 8), Red Hat Enterprise Linux RT (v. 8) · released 2026-10-05 · [advisory](https://access.redhat.com/errata/RHSA-2026:75746) - **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 9 · updated 2026-10-26 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-45856.json) **kernel: RDMA/uverbs: Validate wqe_size before using it in ib_uverbs_post_send** — rated Moderate by Red Hat. Released 2026-05-27, updated 2026-10-26. Affected: - Red Hat Enterprise Linux 6 - Red Hat Enterprise Linux 7 - Red Hat Enterprise Linux 9 Fixed: - 10Base-SMTV - Red Hat Enterprise Linux AppStream (v. 10) - Red Hat Enterprise Linux AppStream (v. 9) - Red Hat Enterprise Linux BaseOS (v. 10) - Red Hat Enterprise Linux BaseOS (v. 8) - Red Hat Enterprise Linux BaseOS (v. 9) - Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) - Red Hat Enterprise Linux CRB (v. 8) - Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) - Red Hat Enterprise Linux Hidden (v. 10) - Red Hat Enterprise Linux Real Time for NFV (v. 10) - Red Hat Enterprise Linux NFV (v. 8) - Red Hat Enterprise Linux Real Time for NFV (v. 9) - Red Hat Enterprise Linux Real Time (v. 10) - Red Hat Enterprise Linux RT (v. 8) - Red Hat Enterprise Linux Real Time (v. 9) No fix planned: - Red Hat Enterprise Linux 6 - Red Hat Enterprise Linux 7 - Red Hat Enterprise Linux 9 ## Remediation For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 The system must be rebooted for this update to take effect. Red Hat recommends treating all kernel errata as security-relevant. Given the kernel's fundamental role, any bug has a higher chance of impacting system security, even if that impact only becomes clear after a fix is published. Therefore, Red Hat prioritizes delivering fixes that improve our customers' overall security posture. Because of this proactive approach, a patch may be associa… https://access.redhat.com/errata/RHSA-2026:76738 For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 The system must be rebooted for this update to take effect. Red Hat recommends treating all kernel errata as security-relevant. Given the kernel's fundamental role, any bug has a higher chance of impacting system security, even if that impact only becomes clear after a fix is published. Therefore, Red Hat prioritizes delivering fixes that improve our customers' overall security posture. Because of this proactive approach, a patch may be associa… https://access.redhat.com/errata/RHSA-2026:74438 For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 The system must be rebooted for this update to take effect. Red Hat recommends treating all kernel errata as security-relevant. Given the kernel's fundamental role, any bug has a higher chance of impacting system security, even if that impact only becomes clear after a fix is published. Therefore, Red Hat prioritizes delivering fixes that improve our customers' overall security posture. Because of this proactive approach, a patch may be associa… https://access.redhat.com/errata/RHSA-2026:75747