Out-of-bounds write in Linux kernel - CVE-2026-63825

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Main Vulnerability Database Vulnerabilities #VU138832

Out-of-bounds write in Linux kernel - CVE-2026-63825

Published: July 21, 2026


Vulnerability identifier: #VU138832
CSH Severity: Low
CVSS v4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-63825
CWE-ID: CWE-787
Exploitation vector: Local access
Exploit availability: No public exploit available

Vulnerability details

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

The vulnerability exists due to an out-of-bounds write in inflate_fast() when processing IP payload compression data concurrently on multiple cpus. A local user can trigger concurrent execution of the vulnerable code path to cause a denial of service.

The issue occurs because global gcov counters can change between multiple loads during execution, producing inconsistent loop values.


Affected software

Linux kernel
Debian Linux
openEuler
Ubuntu
bpftool
kernel
python3-perf-debuginfo
python3-perf
perf-debuginfo
perf
kernel-tools-devel
kernel-tools-debuginfo
kernel-tools
kernel-source
kernel-headers
kernel-devel
kernel-debugsource
kernel-debuginfo
bpftool-debuginfo
linux-nvidia-tegra (Ubuntu package)
linux (Debian package)
linux (Ubuntu package)
linux-gcp-7.0 (Ubuntu package)
linux-oracle-7.0 (Ubuntu package)
linux-azure (Ubuntu package)
linux-oem-7.0 (Ubuntu package)
linux-ibm (Ubuntu package)
linux-azure-7.0 (Ubuntu package)
linux-nvidia-7.0 (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-raspi (Ubuntu package)
linux-nvidia-bos (Ubuntu package)

How to mitigate CVE-2026-63825

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
bpftool - update to 5.10.0-327.0.0.228
kernel - update to 5.10.0-327.0.0.228
python3-perf-debuginfo - update to 5.10.0-327.0.0.228
python3-perf - update to 5.10.0-327.0.0.228
perf-debuginfo - update to 5.10.0-327.0.0.228
perf - update to 5.10.0-327.0.0.228
kernel-tools-devel - update to 5.10.0-327.0.0.228
kernel-tools-debuginfo - update to 5.10.0-327.0.0.228
kernel-tools - update to 5.10.0-327.0.0.228
kernel-source - update to 5.10.0-327.0.0.228
kernel-headers - update to 5.10.0-327.0.0.228
kernel-devel - update to 5.10.0-327.0.0.228
kernel-debugsource - update to 5.10.0-327.0.0.228
kernel-debuginfo - update to 5.10.0-327.0.0.228
bpftool-debuginfo - update to 5.10.0-327.0.0.228
linux-nvidia-tegra (Ubuntu package) - update to 6.8.0-1035.38
linux (Debian package) - update to 6.12.115-2
linux (Ubuntu package) - addressed in versions 7.0.0-31.31~24.04.1, 7.0.0-31.31, 7.0.0-31.31.1, 7.0.0-1006.7, 7.0.0-1011.11~24.04.1, 7.0.0-1012.12~24.04.1, 7.0.0-1012.12
linux-gcp-7.0 (Ubuntu package) - update to 7.0.0-1011.11~24.04.1
linux-oracle-7.0 (Ubuntu package) - update to 7.0.0-1011.11~24.04.1
linux-azure (Ubuntu package) - addressed in versions 7.0.0-1011.11, 7.0.0-1014.14
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1013.13
linux-ibm (Ubuntu package) - update to 7.0.0-1013.13
linux-azure-7.0 (Ubuntu package) - update to 7.0.0-1014.14~24.04.1
linux-nvidia-7.0 (Ubuntu package) - update to 7.0.0-1018.18~24.04.1
linux-nvidia (Ubuntu package) - update to 7.0.0-1018.18
linux-raspi (Ubuntu package) - update to 7.0.0-1019.19
linux-nvidia-bos (Ubuntu package) - update to 7.0.0-2018.18

External References

Related Security Bulletins