CVE-2026-63809
Description
A flaw was found in the Linux kernel. An issue in the BPF (Berkeley Packet Filter) subsystem's sysctl handling can lead to memory corruption. Specifically, when a temporary buffer is allocated using kvzalloc() but incorrectly freed with kfree(), it can corrupt memory. A local attacker could exploit this vulnerability to cause a system crash, leading to a denial of service.
Statement
This vulnerability is rated as Moderate severity for Red Hat Enterprise Linux because exploiting it requires privileged access to attach cgroup-scoped BPF programs and write large payloads to sysctl entries, limiting the blast radius to a local denial of service. Under default enterprise configurations, unprivileged users cannot attach control group filters or manipulate protected kernel parameters in a manner that triggers the improper memory deallocation. Consequently, an attacker must already possess administrative privileges on the host system to trigger an unexpected kernel crash.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.4 | N/A | 7.8 |
| Attack Vector | Local | N/A | Local |
| Attack Complexity | High | N/A | Low |
| Privileges Required | High | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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