USN-8373-1: Linux kernel vulnerabilities

It was discovered that the Linux kernel did not properly handle shared page fragments during socket buffer operations, collectively known as Dirty Frag. A logic flaw existed in the XFRM ESP-in-TCP subsystem and in the RxRPC networking subsystem when processing paged fragments. A local attacker could use this to escalate privileges, or possibly escape a container. (CVE-2026-43284, CVE-2026-43500, CVE-2026-45998, CVE-2026-46000) It was discovered that a logic flaw existed in the XFRM ESP-in-TCP subsystem in the Linux kernel when handling socket buffer fragments. This flaw is known as Fragnesia. A local attacker could use this to escalate privileges, or possibly escape a container. (CVE-2026-43503, CVE-2026-46300) Qualys discovered that a race condition existed in the ptrace subsystem of the Linux kernel when privileged processes are exiting. An unprivileged local attacker could use this issue to expose sensitive information. (CVE-2026-46333) Tristan Madani discovered that Ubuntu Linux kernel 6.8, 6.17 and 7.0 contain a memory leak when handling AppArmor notifications. A local attacker could use this to cause resource exhaustion. (CVE-2026-47326) Tristan Madani discovered that Ubuntu Linux kernel 6.8, 6.17 and 7.0 contain a NULL pointer dereference when handling AppArmor notifications. A local attacker could use this to cause a kernel oops. (CVE-2026-47327) Tristan Madani discovered that Ubuntu Linux kernel 6.8, 6.17 and 7.0 contained an invalid free when handling AppArmor notifications. A local attacker could use this to corrupt kernel memory. (CVE-2026-47328) Tristan Madani discovered that Ubuntu Linux kernel 6.8, 6.17 and 7.0 contained insufficient validation of AppArmor notification responses. A local attacker could use this to allow crafted responses to be processed. (CVE-2026-47329) Tristan Madani discovered that Ubuntu Linux kernel 6.8, 6.17 and 7.0 used an uninitialized variable when handling AppArmor notifications. A local attacker could use this to cause incorrect caching of data. (CVE-2026-47330) Tristan Madani discovered that Ubuntu Linux kernel 6.8 contained a use- after-free (UAF) bug. A local attacker could use this to cause memory corruption and, theoretically, arbitrary code execution. (CVE-2026-47331) Tristan Madani discovered that Ubuntu Linux kernel 6.8, 6.17 and 7.0 contained an out-of-bounds (OOB) read when handling AppArmor notifications. A local attacker could use this to cause information disclosure of kernel memory. (CVE-2026-47332) Tristan Madani discovered that Ubuntu Linux kernel 6.8, 6.17 and 7.0 contained a out-of-bounds (OOB) read when handling AppArmor notifications. A local attacker could use this to cause kernel memory corruption and, theoretically, influence processing of AppArmor policies. (CVE-2026-47333) Tristan Madani discovered that Ubuntu Linux kernel 6.8, 6.17 and 7.0 contained incorrect holding of locks when handling AppArmor notifications. A local attacker could use this to cause a kernel panic or deadlock. (CVE-2026-47334) Tristan Madani discovered that Ubuntu Linux kernel 6.8 contained a NULL pointer dereference when handling AppArmor notifications. A local attacker could use this to cause a kernel panic. (CVE-2026-47335) Tristan Madani discovered that Ubuntu Linux kernel 6.8 used an uninitialized variable when handling AppArmor AF_INET/AF_INET6 socket mediation. A local attacker could use this to influence processing of fine- grained network socket mediation. (CVE-2026-47336) Tristan Madani and Trevor Lawrence have each independently discovered that Ubuntu Linux kernel 6.8, 6.17 and 7.0 contained a NULL pointer dereference when handling AppArmor network socket mediation. A local attacker could use this to cause a kernel oops. (CVE-2026-47337) Several security issues were discovered in the Linux kernel. An attacker could possibly use these to compromise the system. This update corrects flaws in the following subsystems: - RDS protocol; - RxRPC session sockets; (CVE-2026-31676, CVE-2026-43494)