{"id":"CVE-2026-45856","title":"RDMA/uverbs: Validate wqe_size before using it in ib_uverbs_post_send","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nRDMA/uverbs: Validate wqe_size before using it in ib_uverbs_post_send\n\nib_uverbs_post_send() uses cmd.wqe_size from userspace without any\nvalidation before passing it t…","severity":"high","cvss":7.1,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= c3bea3d2dc5358e05541527283279102383b0231 < 9c15ec4cd4e7f57c6bbcb4e73e99290f150dd2a7","Linux >= c3bea3d2dc5358e05541527283279102383b0231 < 9b5ac1c15334d46c0dbd49d64a2257b929500163","Linux >= c3bea3d2dc5358e05541527283279102383b0231 < 01c9b152647dc70dc06a4a2eff86ebb3b3c76075","Linux >= c3bea3d2dc5358e05541527283279102383b0231 < bf1feed1a7886af945f92890493aefd2b5c9928a","Linux >= c3bea3d2dc5358e05541527283279102383b0231 < d533425ac1f2925b4fc3e4ed9b9d72362cb23475","Linux >= c3bea3d2dc5358e05541527283279102383b0231 < bf4454da8b1e712714628c0a0d6e7845bb40790a","Linux >= c3bea3d2dc5358e05541527283279102383b0231 < bef70ff9841990658610512b4a18e4a88c9b4df6","Linux >= c3bea3d2dc5358e05541527283279102383b0231 < 1956f0a74ccf5dc9c3ef717f2985c3ed3400aab0","Linux 5.0"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-10-16T15:18:02.441726Z"},"published":"2026-05-27","updated":"2026-10-16","sourceUpdated":"2026-10-16T15:20:44.029Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-45856","references":[{"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":["cve.org"],"epss":0.00165,"epssPercentile":0.05306,"ingestedAt":"2026-10-16T17:24:46.699Z","slug":"CVE-2026-45856","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nRDMA/uverbs: Validate wqe_size before using it in ib_uverbs_post_send\n\nib_uverbs_post_send() uses cmd.wqe_size from userspace without any\nvalidation before passing it to kmalloc() and using the allocated\nbuffer as struct ib_uverbs_send_wr.\n\nIf a user provides a small wqe_size value (e.g., 1), kmalloc() will\nsucceed, but subsequent accesses to user_wr->opcode, user_wr->num_sge,\nand other fields will read beyond the allocated buffer, resulting in\nan out-of-bounds read from kernel heap memory. This could potentially\nleak sensitive kernel information to userspace.\n\nAdditionally, providing an excessively large wqe_size can trigger a\nWARNING in the memory allocation path, as reported by syzkaller.\n\nThis is inconsistent with ib_uverbs_unmarshall_recv() which properly\nvalidates that wqe_size >= sizeof(struct ib_uverbs_recv_wr) before\nproceeding.\n\nAdd the same validation for ib_uverbs_post_send() to ensure wqe_size\nis at least sizeof(struct ib_uverbs_send_wr).\n\n## Affected\n\n- `Linux >= c3bea3d2dc5358e05541527283279102383b0231 < 9c15ec4cd4e7f57c6bbcb4e73e99290f150dd2a7`\n- `Linux >= c3bea3d2dc5358e05541527283279102383b0231 < 9b5ac1c15334d46c0dbd49d64a2257b929500163`\n- `Linux >= c3bea3d2dc5358e05541527283279102383b0231 < 01c9b152647dc70dc06a4a2eff86ebb3b3c76075`\n- `Linux >= c3bea3d2dc5358e05541527283279102383b0231 < bf1feed1a7886af945f92890493aefd2b5c9928a`\n- `Linux >= c3bea3d2dc5358e05541527283279102383b0231 < d533425ac1f2925b4fc3e4ed9b9d72362cb23475`\n- `Linux >= c3bea3d2dc5358e05541527283279102383b0231 < bf4454da8b1e712714628c0a0d6e7845bb40790a`\n- `Linux >= c3bea3d2dc5358e05541527283279102383b0231 < bef70ff9841990658610512b4a18e4a88c9b4df6`\n- `Linux >= c3bea3d2dc5358e05541527283279102383b0231 < 1956f0a74ccf5dc9c3ef717f2985c3ed3400aab0`\n- `Linux 5.0`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":39,"depthScoreParts":{"impact":39.1,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}