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{"bugzilla": {"description": "kernel: Linux kernel BPF protection against speculative execution attacks can be bypassed to read arbitrary kernel memory", "id": "1974456", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=1974456"}, "csaw": false, "cvss3": {"cvss3_base_score": "4.7", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N", "status": "draft"}, "cwe": "CWE-119", "details": ["In kernel/bpf/verifier.c in the Linux kernel before 5.12.13, a branch can be mispredicted (e.g., because of type confusion) and consequently an unprivileged BPF program can read arbitrary memory locations via a side-channel attack, aka CID-9183671af6db.", "A flaw was found in the Linux kernel's BPF subsystem, where protection against speculative execution attacks (Spectre mitigation) can be bypassed. The highest threat from this vulnerability is to confidentiality."], "mitigation": {"lang": "en:us", "value": "The default Red Hat Enterprise Linux kernel setting prevents unprivileged users from being able to use eBPF via the kernel.unprivileged_bpf_disabled sysctl. As such, exploiting this issue would require a privileged user with CAP_SYS_ADMIN or root.\nFor the Red Hat Enterprise Linux 7 the eBPF for unprivileged users is always disabled. For the Red Hat Enterprise Linux 8 to confirm the current state, inspect the sysctl with the command:\ncat /proc/sys/kernel/unprivileged_bpf_disabled\nThe setting of 1 (default) would mean that unprivileged users cannot use eBPF. Otherwise, to disable eBPF for unprivileged users, add:\nkernel.unprivileged_bpf_disabled = 1\nTo the file \"/etc/sysctl.d/disable-ebpf.conf\"\nThen running the following command as root:\n# sudo sysctl --system"}, "name": "CVE-2021-33624", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Will not fix", "package_name": "kernel-alt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Out of support scope", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2021-06-21T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2021-33624\nhttps://nvd.nist.gov/vuln/detail/CVE-2021-33624\nhttps://github.com/torvalds/linux/commit/9183671af6dbf60a1219371d4ed73e23f43b49db\nhttps://www.openwall.com/lists/oss-security/2021/06/21/1"], "threat_severity": "Moderate"}