CVE-2026-45856
HighCVSS 7.1Exploitation Probability (EPSS)
Low risk6th percentile - higher than 6% of all known CVEs
Summary
A vulnerability has been identified in the Linux kernel in the ib_uverbs_post_send() function, which does not validate the wqe_size value before use. This allows reading beyond the allocated buffer, potentially leaking sensitive kernel information.
Risk Assessment
This vulnerability poses a risk of leaking sensitive kernel information to userspace, which could be exploited by a malicious user for privilege escalation or other attacks.
Recommendation
It is recommended to update the Linux kernel to a version that includes a fix validating the wqe_size in the ib_uverbs_post_send() function.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: RDMA/uverbs: Validate wqe_size before using it in ib_uverbs_post_send ib_uverbs_post_send() uses cmd.wqe_size from userspace without any validation before passing it to kmalloc() and using the allocated buffer as struct ib_uverbs_send_wr. If a user provides a small wqe_size value (e.g., 1), kmalloc() will succeed, but subsequent accesses to user_wr->opcode, user_wr->num_sge, and other fields will read beyond the allocated buffer, resulting in an out-of-bounds read from kernel heap memory. This could potentially leak sensitive kernel information to userspace. Additionally, providing an excessively large wqe_size can trigger a WARNING in the memory allocation path, as reported by syzkaller. This is inconsistent with ib_uverbs_unmarshall_recv() which properly validates that wqe_size >= sizeof(struct ib_uverbs_recv_wr) before proceeding. Add the same validation for ib_uverbs_post_send() to ensure wqe_size is at least sizeof(struct ib_uverbs_send_wr).