Out-of-bounds read in Linux kernel - CVE-2026-63888

Vulnerability identifier: #VU138772

CSH Severity: Medium

CVSS v4: 7.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-63888

CWE-ID: CWE-125

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote user to cause a denial of service.

The vulnerability exists due to an out-of-bounds read in iscsit_handle_text_cmd() when processing Text PDUs with DataDigest enabled. A remote user can send a specially crafted text request to cause a denial of service.

The issue is triggered when DataDigest is negotiated for the connection.

Linux kernel
Red Hat Enterprise Linux for Real Time
Red Hat Enterprise Linux for Real Time for NFV
Anolis OS
Red Hat Enterprise Linux Server - AUS
openEuler
Ubuntu
kernel (Red Hat package)
kernel-rt (Red Hat package)
kernel-modules-extra
kernel-tools-libs-devel
kernel-tools-libs
kernel-tools
bpftool
kernel
kernel-core
kernel-cross-headers
kernel-debug
kernel-debug-core
kernel-debug-modules
kernel-doc
kernel-abi-stablelists
python3-perf
perf
kernel-modules
kernel-headers
kernel-devel
kernel-debug-modules-extra
kernel-debug-devel
kernel-source
python3-perf-debuginfo
python2-perf-debuginfo
python2-perf
perf-debuginfo
kernel-tools-devel
kernel-debugsource
kernel-debuginfo
bpftool-debuginfo
kernel-tools-debuginfo
kernel-extra-modules
linux-ibm (Ubuntu package)
linux-aws (Ubuntu package)
linux-azure (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-nvidia-bos (Ubuntu package)

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
kernel (Red Hat package) - update to 4.18.0-372.208.1.el8_6
kernel-rt (Red Hat package) - update to 4.18.0-553.157.1.rt7.498.el8_10
kernel-modules-extra - update to 4.18.0-553.157.1.0.1
kernel-tools-libs-devel - update to 4.18.0-553.157.1.0.1
kernel-tools-libs - update to 4.18.0-553.157.1.0.1
kernel-tools - update to 4.18.0-553.157.1.0.1
bpftool - update to 4.18.0-553.157.1.0.1
kernel - update to 4.18.0-553.157.1.0.1
kernel-core - update to 4.18.0-553.157.1.0.1
kernel-cross-headers - update to 4.18.0-553.157.1.0.1
kernel-debug - update to 4.18.0-553.157.1.0.1
kernel-debug-core - update to 4.18.0-553.157.1.0.1
kernel-debug-modules - update to 4.18.0-553.157.1.0.1
kernel-doc - update to 4.18.0-553.157.1.0.1
kernel-abi-stablelists - update to 4.18.0-553.157.1.0.1
python3-perf - update to 4.18.0-553.157.1.0.1
perf - update to 4.18.0-553.157.1.0.1
kernel-modules - update to 4.18.0-553.157.1.0.1
kernel-headers - update to 4.18.0-553.157.1.0.1
kernel-devel - update to 4.18.0-553.157.1.0.1
kernel-debug-modules-extra - update to 4.18.0-553.157.1.0.1
kernel-debug-devel - update to 4.18.0-553.157.1.0.1
kernel-source - addressed in versions 4.19.90-2608.2.0.0384, 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
python3-perf-debuginfo - addressed in versions 4.19.90-2608.2.0.0384, 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
python3-perf - addressed in versions 4.19.90-2608.2.0.0384, 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
python2-perf-debuginfo - update to 4.19.90-2608.2.0.0384
python2-perf - update to 4.19.90-2608.2.0.0384
perf-debuginfo - addressed in versions 4.19.90-2608.2.0.0384, 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
perf - addressed in versions 4.19.90-2608.2.0.0384, 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
kernel-tools-devel - addressed in versions 4.19.90-2608.2.0.0384, 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
kernel-tools - addressed in versions 4.19.90-2608.2.0.0384, 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
kernel-devel - addressed in versions 4.19.90-2608.2.0.0384, 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
kernel-debugsource - addressed in versions 4.19.90-2608.2.0.0384, 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
kernel-debuginfo - addressed in versions 4.19.90-2608.2.0.0384, 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
bpftool-debuginfo - addressed in versions 4.19.90-2608.2.0.0384, 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
bpftool - addressed in versions 4.19.90-2608.2.0.0384, 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
kernel - addressed in versions 4.19.90-2608.2.0.0384, 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
kernel-tools-debuginfo - addressed in versions 4.19.90-2608.2.0.0384, 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
kernel-headers - addressed in versions 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
kernel-extra-modules - update to 6.6.0-145.3.29.160
linux-ibm (Ubuntu package) - addressed in versions 7.0.0-1008.8, 7.0.0-1010.10
linux-aws (Ubuntu package) - addressed in versions 7.0.0-1009.9, 7.0.0-1015.15
linux-azure (Ubuntu package) - addressed in versions 7.0.0-1009.9, 7.0.0-1010.10
linux-nvidia (Ubuntu package) - addressed in versions 7.0.0-1016.16, 7.0.0-1016.16~24.04.1
linux-nvidia-bos (Ubuntu package) - update to 7.0.0-2016.16

• https://git.kernel.org/stable/c/5118ea225fe63b44207ba88047e4866e1ea43812
• https://git.kernel.org/stable/c/6e22a1cdcc8277af4acc43710577157b77a02c5d
• https://git.kernel.org/stable/c/778c2ab142c625a8a8afa570e0f9b7873f445d99
• https://git.kernel.org/stable/c/89c81d1228c00fa6dd91de6c1c5aa1ef8a7875e3
• https://git.kernel.org/stable/c/badf178b76b0690851df00f4ca9cf2eb8eb0f963
• https://git.kernel.org/stable/c/d3e9b79aa794f7a23e82de4d710e7d2df610e349
• https://git.kernel.org/stable/c/ec9f19d52074a191ed1756ed4a7d39fff1a2085c
• https://git.kernel.org/stable/c/f7948af0dd03de84079dcd4dc215a69fd6fbb95d

• Out-of-bounds read in Linux kernel target iscsi driver
• Ubuntu update for linux-ibm
• Ubuntu update for linux-azure
• Ubuntu update for linux-aws
• openEuler 22.03 LTS SP4 update for kernel
• openEuler 20.03 LTS SP4 update for kernel
• Red Hat Enterprise Linux 8 update for kernel-rt
• Ubuntu update for linux-nvidia-bos
• Ubuntu update for linux-nvidia
• Red Hat Enterprise Linux 8 update for kernel
• Anolis OS update for kernel:4.18
• openEuler 24.03 LTS SP3 update for kernel