cve 2026 63809

The cve 2026 63809 tag covers a Linux kernel memory-corruption flaw affecting the eBPF cgroup sysctl path. It is relevant to Windows users running Windows Subsystem for Linux 2 (WSL 2), as well as administrators managing Linux servers, containers, and development hosts. The issue can trigger a kernel crash when a sysctl write buffer uses a virtual-memory allocation fallback, caused by an allocator mismatch. The documented fix replaces kfree() with kvfree(). The vulnerability record was published by the National Vulnerability Database on July 19, 2026, while no CVSS score or severity rating had been assigned at the time of the supplied report.