CVE-2026-98361

7.8 HIGH

Published 2026-10-06 · Updated 2026-10-07

AI risk analysis

Summary: The Linux kernel's RDMA/rxe driver had a missing permission check that allowed unprivileged users to overwrite read-only file pages through RDMA operations, creating a Dirty COW-like vulnerability where attackers could modify protected files like /etc/passwd or setuid binaries without proper write permissions.
Exploitability: Exploitation requires an unprivileged user to register an ODP MR over a read-only mapping and receive RDMA traffic that triggers page faults, which is moderately difficult but possible in environments with RDMA support.
Blast radius: The vulnerability could affect any system running Linux kernel with rxe RDMA driver enabled, potentially allowing attackers to modify critical system files and setuid binaries, leading to privilege escalation or persistent backdoors.
Detection: No reliable host or network indicator is derivable from the published description.
Prioritized remediation: Upgrade to Linux kernel version 5.19.0 or later where the fix for commit 0b261d7c1cd3 is included.

rdmamemoryprivilege-escalationkernel

Analysis generated locally by garnet-coder (no data left the box). AI-assisted — verify against primary sources before acting.

NVD description

In the Linux kernel, the following vulnerability has been resolved: RDMA/rxe: Restore HMM_PFN_WRITE check in ODP write paths Commit 0b261d7c1cd3 ("RDMA/rxe: Break endless pagefault loop for RO pages") dropped the access permission test from rxe_check_pagefault() and left only HMM_PFN_VALID. A page faulted in read-only, for example a page-cache folio behind a PROT_READ file mapping, then satisfies the check and ODP write operations (RDMA WRITE, RDMA READ response, SEND payload, atomics) modify it through kmap without ever breaking CoW. An unprivileged user can register an ODP MR over such a mapping and have incoming RDMA traffic overwrite the page cache of a file it only holds O_RDONLY, including /etc/passwd or setuid binaries. This is the same primitive class as Dirty COW and CVE-2022-2590. mlx5 has the missing invariant: its ODP path sets the device write bit only for pfns that carry HMM_PFN_WRITE. Restore it in rxe by requiring HMM_PFN_WRITE in rxe_check_pagefault() for every operation except RXE_PAGEFAULT_RDONLY. A write to a non-writable VMA now fails the one fault attempt with -EPERM from hmm_vma_fault() instead of re-faulting forever. For a writable VMA the fault breaks CoW and the write lands in the private page. Keep pmem flushes on the read-only check. arch_wb_cache_pmem() never modifies memory, and the FLUSH access bits do not make the umem writable, so classifying flushes as writes would make every flush against a flush-only MR fail.

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

All references

Source data: NVD (nvd.nist.gov), public domain. Exploit-DB.ai adds local AI analysis for defensive use only.

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