CVE-2026-63809: bpf: use kvfree() for replaced sysctl write buffer

mediumCVSS 5.5CVE-2026-63809

CSIRTS triage

vendor: Linux product: bpfOther

What: This vulnerability uses kvfree() for the replaced sysctl write buffer.
Who is affected: Deployments using the bpf subsystem.
Urgency: Remediation is necessary to prevent potential memory issues, although exploitation is not currently reported.
Action: Use kvfree() for the replaced sysctl write buffer.

AI-assisted analysis generated from the source advisory — verify against the original.

⚡ Watch bpf

Get an email when a new bpf advisory drops — max one per day, one-click unsubscribe.

Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: medium — CVSS 5.5
Published: 2026-07-14
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-63809

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-638090.15% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 5% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-63809	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

Recent advisories for bpf

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

highCVE-2026-64548: In the Linux kernel, the following vulnerability has been resolved: bpf, sockmap: reject overf…nvd · 2026-07-27
highCVE-2026-64545: In the Linux kernel, the following vulnerability has been resolved: net, bpf: check master for…nvd · 2026-07-27
unknownCVE-2026-64508: In the Linux kernel, the following vulnerability has been resolved: bpf: Support for hardening…nvd · 2026-07-25
unknownCVE-2026-64507: In the Linux kernel, the following vulnerability has been resolved: x86/bugs: Enable IBPB flus…nvd · 2026-07-25
criticalCVE-2026-64355: In the Linux kernel, the following vulnerability has been resolved: bpf: Reject fragmented fra…nvd · 2026-07-25
highCVE-2026-64354: In the Linux kernel, the following vulnerability has been resolved: bpf: Validate BTF repeated…nvd · 2026-07-25