{"id":"USN-5091-3","aliases":[],"status":"published","title":"linux-azure, linux-azure-5.4 regression","description":"USN-5091-1 fixed vulnerabilities in Linux 5.4-based kernels.\nUnfortunately, for Linux kernels intended for use within Microsoft\nAzure environments, that update introduced a regression that could\ncause the kernel to fail to boot in large Azure instance types.\nThis update fixes the problem.\n\nWe apologize for the inconvenience.\n\nOriginal advisory details:\n\n Ofek Kirzner, Adam Morrison, Benedict Schlueter, and Piotr Krysiuk\n discovered that the BPF verifier in the Linux kernel missed possible\n mispredicted branches due to type confusion, allowing a side-channel\n attack. An attacker could use this to expose sensitive information.\n (CVE-2021-33624)\n\n It was discovered that the tracing subsystem in the Linux kernel did not\n properly keep track of per-cpu ring buffer state. A privileged attacker\n could use this to cause a denial of service. (CVE-2021-3679)\n\n Alexey Kardashevskiy discovered that the KVM implementation for PowerPC\n systems in the Linux kernel did not properly validate RTAS arguments in\n some situations. An attacker in a guest vm could use this to cause a denial\n of service (host OS crash) or possibly execute arbitrary code.\n (CVE-2021-37576)\n\n It was discovered that the Virtio console implementation in the Linux\n kernel did not properly validate input lengths in some situations. A local\n attacker could possibly use this to cause a denial of service (system\n crash). (CVE-2021-38160)\n\n Michael Wakabayashi discovered that the NFSv4 client implementation in the\n Linux kernel did not properly order connection setup operations. An\n attacker controlling a remote NFS server could use this to cause a denial\n of service on the client. (CVE-2021-38199)\n\n It was discovered that the MAX-3421 host USB device driver in the Linux\n kernel did not properly handle device removal events. A physically\n proximate attacker could use this to cause a denial of service (system\n crash). (CVE-2021-38204)","facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"published":"2021-10-15T00:11:45Z","modified":"2026-02-10T04:42:19Z","fixes":[{"ecosystem":"Ubuntu:18.04:LTS","package":"linux-azure-5.4","fixed_in":["5.4.0-1061.64~18.04.1"],"sources":["osv"]},{"ecosystem":"Ubuntu:20.04:LTS","package":"linux-azure","fixed_in":["5.4.0-1061.64"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Ubuntu:18.04:LTS","package":"linux-azure-5.4","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1061.64~18.04.1"}]}],"versions":["5.4.0-1020.20~18.04.1","5.4.0-1022.22~18.04.1","5.4.0-1023.23~18.04.1","5.4.0-1025.25~18.04.1","5.4.0-1026.26~18.04.1","5.4.0-1031.32~18.04.1","5.4.0-1032.33~18.04.1","5.4.0-1034.35~18.04.1","5.4.0-1035.36~18.04.1","5.4.0-1036.38~18.04.1","5.4.0-1039.41~18.04.1","5.4.0-1040.42~18.04.1","5.4.0-1041.43~18.04.1","5.4.0-1043.45~18.04.1","5.4.0-1044.46~18.04.1","5.4.0-1046.48~18.04.1","5.4.0-1047.49~18.04.1","5.4.0-1048.50~18.04.1","5.4.0-1049.51~18.04.1","5.4.0-1051.53~18.04.1","5.4.0-1055.57~18.04.1","5.4.0-1056.58~18.04.1","5.4.0-1058.60~18.04.1","5.4.0-1059.62~18.04.1"]},{"source":"osv","ecosystem":"Ubuntu:20.04:LTS","package":"linux-azure","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1061.64"}]}],"versions":["5.3.0-1003.3","5.3.0-1008.9","5.3.0-1009.10","5.4.0-1006.6","5.4.0-1008.8","5.4.0-1009.9","5.4.0-1010.10","5.4.0-1012.12","5.4.0-1016.16","5.4.0-1019.19","5.4.0-1020.20","5.4.0-1022.22","5.4.0-1023.23","5.4.0-1025.25","5.4.0-1026.26","5.4.0-1031.32","5.4.0-1032.33","5.4.0-1034.35","5.4.0-1035.36","5.4.0-1036.38","5.4.0-1039.41","5.4.0-1040.42","5.4.0-1041.43","5.4.0-1043.45","5.4.0-1044.46","5.4.0-1046.48","5.4.0-1047.49","5.4.0-1048.50","5.4.0-1049.51","5.4.0-1051.53","5.4.0-1055.57","5.4.0-1056.58","5.4.0-1058.60","5.4.0-1059.62"]}],"references":[{"url":"https://ubuntu.com/security/notices/USN-5091-3","tags":["advisory"]},{"url":"https://launchpad.net/bugs/1940564","tags":["report"]}],"sources":{"osv":[{"id":"USN-5091-3","title":"linux-azure, linux-azure-5.4 regression","description":"USN-5091-1 fixed vulnerabilities in Linux 5.4-based kernels.\nUnfortunately, for Linux kernels intended for use within Microsoft\nAzure environments, that update introduced a regression that could\ncause the kernel to fail to boot in large Azure instance types.\nThis update fixes the problem.\n\nWe apologize for the inconvenience.\n\nOriginal advisory details:\n\n Ofek Kirzner, Adam Morrison, Benedict Schlueter, and Piotr Krysiuk\n discovered that the BPF verifier in the Linux kernel missed possible\n mispredicted branches due to type confusion, allowing a side-channel\n attack. An attacker could use this to expose sensitive information.\n (CVE-2021-33624)\n\n It was discovered that the tracing subsystem in the Linux kernel did not\n properly keep track of per-cpu ring buffer state. A privileged attacker\n could use this to cause a denial of service. (CVE-2021-3679)\n\n Alexey Kardashevskiy discovered that the KVM implementation for PowerPC\n systems in the Linux kernel did not properly validate RTAS arguments in\n some situations. An attacker in a guest vm could use this to cause a denial\n of service (host OS crash) or possibly execute arbitrary code.\n (CVE-2021-37576)\n\n It was discovered that the Virtio console implementation in the Linux\n kernel did not properly validate input lengths in some situations. A local\n attacker could possibly use this to cause a denial of service (system\n crash). (CVE-2021-38160)\n\n Michael Wakabayashi discovered that the NFSv4 client implementation in the\n Linux kernel did not properly order connection setup operations. An\n attacker controlling a remote NFS server could use this to cause a denial\n of service on the client. (CVE-2021-38199)\n\n It was discovered that the MAX-3421 host USB device driver in the Linux\n kernel did not properly handle device removal events. A physically\n proximate attacker could use this to cause a denial of service (system\n crash). (CVE-2021-38204)\n","status":"published","published":"2021-10-15T00:11:45Z","modified":"2026-02-10T04:42:19Z","updated_at":"2026-11-02T16:58:15.683829Z"}]}}