Out-of-bounds read in Linux kernel - CVE-2026-63992

Vulnerability identifier: #VU138656

CSH Severity: Medium

CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-63992

CWE-ID: CWE-125

Exploitation vector: Remote access

Exploit availability: No public exploit available

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

The vulnerability exists due to an out-of-bounds read in iptunnel_pmtud_check_icmp() when processing ICMP packets without a valid transport header. A remote attacker can send a specially crafted packet to cause a denial of service.

The issue occurs because the function may be called while the skb transport header is not set.

Linux kernel
openEuler
Ubuntu
kernel-debugsource
python3-perf-debuginfo
python3-perf
perf-debuginfo
perf
kernel-tools-devel
kernel-tools-debuginfo
kernel-tools
kernel-source
kernel-headers
kernel-devel
kernel-debuginfo
bpftool-debuginfo
bpftool
kernel
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-debugsource - addressed in versions 5.10.0-329.0.0.230, 6.6.0-145.3.29.160
python3-perf-debuginfo - addressed in versions 5.10.0-329.0.0.230, 6.6.0-145.3.29.160
python3-perf - addressed in versions 5.10.0-329.0.0.230, 6.6.0-145.3.29.160
perf-debuginfo - addressed in versions 5.10.0-329.0.0.230, 6.6.0-145.3.29.160
perf - addressed in versions 5.10.0-329.0.0.230, 6.6.0-145.3.29.160
kernel-tools-devel - addressed in versions 5.10.0-329.0.0.230, 6.6.0-145.3.29.160
kernel-tools-debuginfo - addressed in versions 5.10.0-329.0.0.230, 6.6.0-145.3.29.160
kernel-tools - addressed in versions 5.10.0-329.0.0.230, 6.6.0-145.3.29.160
kernel-source - addressed in versions 5.10.0-329.0.0.230, 6.6.0-145.3.29.160
kernel-headers - addressed in versions 5.10.0-329.0.0.230, 6.6.0-145.3.29.160
kernel-devel - addressed in versions 5.10.0-329.0.0.230, 6.6.0-145.3.29.160
kernel-debuginfo - addressed in versions 5.10.0-329.0.0.230, 6.6.0-145.3.29.160
bpftool-debuginfo - addressed in versions 5.10.0-329.0.0.230, 6.6.0-145.3.29.160
bpftool - addressed in versions 5.10.0-329.0.0.230, 6.6.0-145.3.29.160
kernel - addressed in versions 5.10.0-329.0.0.230, 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/43368636c663cff6e59dde93cf4b8e43ac28eb93
• https://git.kernel.org/stable/c/509323077ef79a26ba0c60bb556e45c12c398b2d
• https://git.kernel.org/stable/c/5a92cb45e34749865d03daf8d3500f77b5f6644c
• https://git.kernel.org/stable/c/7f4f7efe7f30edd29c4988de01728bf2398217e4
• https://git.kernel.org/stable/c/a096b6e34f602950af9a2b0856cd93a5f4c276d7
• https://git.kernel.org/stable/c/c7b7ec3e69e673c0d6b57f74d21da50c485c598e
• https://git.kernel.org/stable/c/cb549df9ce4ee15c9d5b19ddab12cf2128e4313c
• https://git.kernel.org/stable/c/e917d0c69f01af2bb4fbea2b66d560a53b3ac7ec

• Out-of-bounds read in Linux kernel ipv4
• Ubuntu update for linux-ibm
• Ubuntu update for linux-azure
• Ubuntu update for linux-aws
• openEuler 22.03 LTS SP4 update for kernel
• Ubuntu update for linux-nvidia-bos
• Ubuntu update for linux-nvidia
• openEuler 24.03 LTS SP3 update for kernel