This USN addresses two specific vulnerabilities in the Linux kernel for Azure: CVE-2025-27558 (CVSS 9.1 Critical), a WiFi mesh network flaw allowing packet injection by a physically proximate attacker, and CVE-2026-43503 (CVSS 8.8 High), a local privilege escalation flaw in the XFRM ESP-in-TCP subsystem known as Fragnesia. CVE-2026-43503 affects kernel versions from 3.9 up to specific fixed versions, such as 5.10.257, 5.15.208, 6.1.174, 6.6.141, 6.12.91, 6.18.33, and 7.0.10. The bulletin also lists numerous other CVEs patched across a wide range of kernel subsystems, but detailed version and scoring information for those is not provided in the source.
Siebe Devroe, Héloïse Gollier, and Mathy Vanhoef discovered that the WiFi implementation in the Linux kernel did not properly handle aggregated frames in mesh networks, due to an incorrect fix for CVE-2020-24588. A physically proximate attacker could use this issue to inject packets. (CVE-2025-27558) 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: - x86 architecture; - Cryptographic API; - GPU drivers; - InfiniBand drivers; - Media drivers; - NVIDIA Tegra memory controller driver; - Network drivers; - STMicroelectronics network drivers; - NVME drivers; - SCSI subsystem; - Thermal drivers; - USB over IP driver; - Ext4 file system; - Network file system (NFS) server daemon; - SMB network file system; - IPv4 networking; - Network traffic control; - TCP network protocol; - Tracing infrastructure; - Locking primitives; - B.A.T.M.A.N. meshing protocol; - Ethernet bridge; - Ceph Core library; - DCCP (Datagram Congestion Control Protocol); - IPv6 networking; - Multipath TCP; - Netfilter; - RxRPC session sockets; - SCTP protocol; - SMC sockets; - X.25 network layer; (CVE-2021-47202, CVE-2021-47354, CVE-2021-47378, CVE-2024-38612, CVE-2024-56643, CVE-2026-23272, CVE-2026-23455, CVE-2026-31402, CVE-2026-31405, CVE-2026-31414, CVE-2026-31448, CVE-2026-31607, CVE-2026-31637, CVE-2026-31649, CVE-2026-31657, CVE-2026-31659, CVE-2026-31668, CVE-2026-31682, CVE-2026-31685, CVE-2026-43011, CVE-2026-43037, CVE-2026-43038, CVE-2026-43198, CVE-2026-43383, CVE-2026-43407, CVE-2026-43414, CVE-2026-43493, CVE-2026-43499, CVE-2026-45988, CVE-2026-46043, CVE-2026-46119, CVE-2026-46243, CVE-2026-46266, CVE-2026-46331, CVE-2026-52924, CVE-2026-52931, CVE-2026-52955, CVE-2026-52982, CVE-2026-52986, CVE-2026-53002, CVE-2026-53006, CVE-2026-53045, CVE-2026-53088, CVE-2026-53176, CVE-2026-53225, CVE-2026-53228, CVE-2026-53359)