The Fragnesia vulnerability (CVE-2026-43503, CVSS 8.8 HIGH) is a logic flaw in the Linux kernel's XFRM ESP-in-TCP subsystem that allows a local attacker to escalate privileges or escape a container by exploiting socket buffer fragment handling. Affected versions include kernel series 3.9 through 7.0 across numerous branches, specifically versions less than 5.10.257, 5.15.208, 6.1.174, 6.6.141, 6.12.91, 6.18.33, and 7.0.10. The security update also patches multiple other vulnerabilities across various subsystems, requiring immediate patching to the specified fixed versions.
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) 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: - InfiniBand drivers; - SCSI subsystem; - Thermal drivers; - USB over IP driver; - Network file system (NFS) server daemon; - SMB network file system; - Tracing infrastructure; - B.A.T.M.A.N. meshing protocol; - Ethernet bridge; - Ceph Core library; - DCCP (Datagram Congestion Control Protocol); - IPv4 networking; - IPv6 networking; - Netfilter; - RxRPC session sockets; - X.25 network layer; (CVE-2021-47202, CVE-2024-56643, CVE-2026-23272, CVE-2026-23455, CVE-2026-31402, CVE-2026-31607, CVE-2026-31637, CVE-2026-31659, CVE-2026-31682, CVE-2026-31685, CVE-2026-43011, CVE-2026-43037, CVE-2026-43038, CVE-2026-43383, CVE-2026-43407, CVE-2026-43414, CVE-2026-45988, CVE-2026-46043, CVE-2026-46119, CVE-2026-46243)