Out-of-bounds write in Linux kernel - CVE-2026-64268

Vulnerability identifier: #VU139713

CSH Severity: High

CVSS v4: 7.2 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-64268

CWE-ID: CWE-787

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote user to write out of bounds.

The vulnerability exists due to an out-of-bounds write in siw_proc_rresp() in drivers/infiniband/sw/siw/siw_qp_rx.c when processing Read Response DDP segments for an outstanding RREAD over an established RDMA connection. A remote user can send Read Response segments with more total payload than requested while keeping the DDP Last flag clear to write out of bounds.

Exploitation requires a connected siw peer on an established RDMA connection over routable TCP.

Linux kernel
Red Hat Enterprise Linux for Real Time
Red Hat Enterprise Linux for Real Time for NFV
Red Hat Enterprise Linux for x86_64
Red Hat Enterprise Linux for IBM z Systems
Red Hat Enterprise Linux for Power, little endian
Red Hat Enterprise Linux for ARM 64
Red Hat CodeReady Linux Builder for x86_64
Red Hat CodeReady Linux Builder for Power, little endian
Red Hat CodeReady Linux Builder for ARM 64
Red Hat Enterprise Linux Server - AUS
Ubuntu
kernel (Red Hat package)
kernel-rt (Red Hat package)
linux (Ubuntu package)
linux-gcp-7.0 (Ubuntu package)
linux-oem-7.0 (Ubuntu package)

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
kernel (Red Hat package) - addressed in versions 4.18.0-305.206.1.el8_4, 4.18.0-553.159.1.el8_10
kernel-rt (Red Hat package) - update to 4.18.0-553.159.1.rt7.500.el8_10
linux (Ubuntu package) - addressed in versions 7.0.0-31.31, 7.0.0-31.31.1, 7.0.0-31.31~24.04.1, 7.0.0-1006.7, 7.0.0-1011.11~24.04.1, 7.0.0-1012.12, 7.0.0-1012.12~24.04.1
linux-gcp-7.0 (Ubuntu package) - update to 7.0.0-1011.11~24.04.1
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1013.13

• https://git.kernel.org/stable/c/3ef7e052cbd05a8b13a51a07b185a39ec93ee1cf
• https://git.kernel.org/stable/c/423a78ff7928c2601013f73ec6d896f5597d0df5
• https://git.kernel.org/stable/c/595e6537ad1a210da32cbb9a7f91aa73090915ba
• https://git.kernel.org/stable/c/6bc89f34a4597f9f6d41f7a60c67a3153bfe8851
• https://git.kernel.org/stable/c/75c93cd3c421890f49ea93f0b978b9b7bb10e5e3
• https://git.kernel.org/stable/c/7d29f7e9dbd844cae4d3e559cf78324b9642fd6b
• https://git.kernel.org/stable/c/a31b6d18ded3cc32d9ee85a6ff0726d4274887b2
• https://git.kernel.org/stable/c/b2e26c955f8dd7e8d3f16c858db05245ea4fa817

• Out-of-bounds write in Linux kernel sw siw driver
• Red Hat Enterprise Linux 8 update for kernel-rt
• Red Hat Enterprise Linux 8 update for kernel
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux
• Ubuntu update for linux-gcp-7.0
• Red Hat Enterprise Linux 8 update for kernel