CVE-2026-63809: In the Linux kernel, the following vulnerability has been resolved: bpf: use kvfree() for replaced sysctl wri

Q: How do I fix CVE-2026-63809?

linux kernel: upgrade to 5.10.260, 5.15.211, 6.1.177, 6.6.144, 6.12.95, 6.18.38, 7.1.3. Exact commands for each OS are on this page.

Q: Is CVE-2026-63809 being exploited?

CVE-2026-63809 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-63809 affect?

CVE-2026-63809 affects linux kernel. Severity is high (CVSS 7.8). In the Linux kernel, the following vulnerability has been resolved: bpf: use kvfree() for replaced sysctl write buffer proc_sys_call_handler() allocates its temporary sysctl buffer with kvzalloc() and passes it to __cgroup_bpf_run_filter_

Q: How urgent is CVE-2026-63809?

Priority 33/100. High severity; On your watchlist

Routine

HIGH 7.8WATCHLISTUPGRADE

CVE-2026-63809 is a high-severity flaw (CVSS 7.8) affecting linux kernel. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In the Linux kernel, the following vulnerability has been resolved: bpf: use kvfree() for replaced sysctl write buffer proc_sys_call_handler() allocates its temporary sysctl buffer with kvzalloc() and passes it to __cgroup_bpf_run_filter_sysctl(). Since kvzalloc() may fall back to vmalloc() for large allocations, freeing that buffer with kfree() is wrong and can corrupt memory. Use kvfree() to safely handle both kmalloc and kvzalloc()/vmalloc

Why this priority

High severity
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	7.8 (High)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.2% (top 96%)
CISA exploited list	No
Weakness	CWE-763, CWE-787
Published	2026-07-19
Last modified	2026-10-22

Publisher (CNA): kernel.org · Vendor: linux

Am I affected?

Timeline

2026-07-19Published CVE record published
2026-10-22 18:46 UTCUpdated Record last modified

linux linux kernel UPGRADE

Affected: >= 5.10.20 and < 5.10.260 · >= 5.11.3 and < 5.15.211 · >= 5.16 and < 6.1.177 · >= 6.2 and < 6.6.144 · >= 6.7 and < 6.12.95 · >= 6.13 and < 6.18.38 · >= 6.19 and < 7.1.3

Fixed in: 5.10.260, 5.15.211, 6.1.177, 6.6.144, 6.12.95, 6.18.38, 7.1.3

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Exact fixes by distribution

Fedora 46 · wasmedge · FIXED · 0.18.1-1.fc46 · FEDORA-2026-4c27216e39 · source

sudo dnf upgrade --advisory=FEDORA-2026-4c27216e39

Ubuntu 20.04 · linux · NOT AFFECTED

Ubuntu 22.04 · linux · FIXED · 5.15.0-198.208

sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "5.15.0-198.208" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 24.04 · linux · FIXED · 6.8.0-147.147

sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "6.8.0-147.147" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 20.04 · linux-hwe-5.15 · FIXED · 5.15.0-198.208~20.04.1

sudo apt update && sudo apt install --only-upgrade linux-hwe-5.15 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux-hwe-5.15)" ge "5.15.0-198.208~20.04.1" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 22.04 · linux-hwe-6.8 · NO FIX YET

Debian 12 · linux · FIXED · 6.1.177-1

sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "6.1.177-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · linux · FIXED · 6.12.95-1

sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "6.12.95-1" && echo PATCHED || echo STILL-VULNERABLE

RHEL 10 · kernel · NO FIX YET

RHEL 6 · kernel · NOT AFFECTED

RHEL 7 · kernel · NOT AFFECTED

RHEL 7 · kernel-rt · NOT AFFECTED

RHEL 8 · kernel · NOT AFFECTED

Amazon Linux 2023 · see advisory · FIXED · ALAS2023-2026-2032 · source

sudo dnf update --advisory=ALAS2023-2026-2032

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-63809?

linux kernel: upgrade to 5.10.260, 5.15.211, 6.1.177, 6.6.144, 6.12.95, 6.18.38, 7.1.3. Exact commands for each OS are on this page.

Is CVE-2026-63809 being exploited?

CVE-2026-63809 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-63809 affect?

CVE-2026-63809 affects linux kernel. Severity is high (CVSS 7.8). In the Linux kernel, the following vulnerability has been resolved: bpf: use kvfree() for replaced sysctl write buffer proc_sys_call_handler() allocates its temporary sysctl buffer with kvzalloc() and passes it to __cgroup_bpf_run_filter_

How urgent is CVE-2026-63809?

Priority 33/100. High severity; On your watchlist

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References

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