Ubuntu 21.04 was released three weeks ago and ships with the Linux 5.11 kernel series by default. The 5.11 kernel has now been patched by the Ubuntu Kernel Team against three recently discovered security vulnerabilities. These include CVE-2021-3489 and CVE-2021-3490, two vulnerabilities discovered by Ryota Shiga and Manfred Paul respectively in Linux kernel?s eBPF implementation. Both of these security issues could allow a local attacker to crash the system by causing a denial of service (DoS attack) or execute arbitrary code.