CVE-2026-46114
HighCVSS 7.5Exploitation Probability (EPSS)
Low risk37th percentile - higher than 37% of all known CVEs
Summary
In the Linux kernel's RDMA/rxe driver, a vulnerability was found due to missing validation of ATOMIC_WRITE payload length. A remote attacker can send a zero-length request, causing 8 bytes beyond the packet end to be read and written to the victim's memory, leading to kernel data leak.
Risk Assessment
An attacker can remotely leak 4 bytes of skb tailroom (including sensitive kernel data like string fragments or pointers) per probe, which may aid in further privilege escalation.
Recommendation
Immediately update the Linux kernel to a version containing the fix (commit adding strict length check in check_rkey()). If update is not possible, temporarily disable the rxe module or restrict trusted RDMA traffic sources.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: RDMA/rxe: Reject non-8-byte ATOMIC_WRITE payloads atomic_write_reply() at drivers/infiniband/sw/rxe/rxe_resp.c unconditionally dereferences 8 bytes at payload_addr(pkt): value = *(u64 *)payload_addr(pkt); check_rkey() previously accepted an ATOMIC_WRITE request with pktlen == resid == 0 because the length validation only compared pktlen against resid. A remote initiator that sets the RETH length to 0 therefore reaches atomic_write_reply() with a zero-byte logical payload, and the responder reads sizeof(u64) bytes from past the logical end of the packet into skb->head tailroom, then writes those 8 bytes into the attacker's MR via rxe_mr_do_atomic_write(). That is a remote disclosure of 4 bytes of kernel tailroom per probe (the other 4 bytes are the packet's own trailing ICRC). IBA oA19-28 defines ATOMIC_WRITE as exactly 8 bytes. Anything else is protocol-invalid. Hoist a strict length check into check_rkey() so the responder never reaches the unchecked dereference, and keep the existing WRITE-family length logic for the normal RDMA WRITE path. Reproduced on mainline with an unmodified rxe driver: a sustained zero-length ATOMIC_WRITE probe repeatedly leaks adjacent skb head-buffer bytes into the attacker's MR, including recognisable kernel strings and partial kernel-direct-map pointer words. With this patch applied the responder rejects the PDU and the MR stays all-zero.