{"id":"CVE-2021-33624","title":"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 C…","summary":"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 C…","severity":"medium","cvss":4.7,"cvssVector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N","cwe":["CWE-843"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel < 5.12.13","debian_linux = 9.0"],"patched":["linux_kernel 5.12.13"],"published":"2021-06-23","updated":"2026-10-08","sourceUpdated":"2026-10-08T21:17:35.550","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2021-33624","references":[{"url":"http://www.openwall.com/lists/oss-security/2021/06/21/1","label":"cve@mitre.org"},{"url":"https://github.com/benschlueter/CVE-2021-33624","label":"cve@mitre.org"},{"url":"https://github.com/torvalds/linux/commit/9183671af6dbf60a1219371d4ed73e23f43b49db","label":"cve@mitre.org"},{"url":"https://lists.debian.org/debian-lts-announce/2021/10/msg00010.html","label":"cve@mitre.org"},{"url":"https://www.usenix.org/conference/usenixsecurity21/presentation/kirzner","label":"cve@mitre.org"},{"url":"http://www.openwall.com/lists/oss-security/2021/06/21/1","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/torvalds/linux/commit/9183671af6dbf60a1219371d4ed73e23f43b49db","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.debian.org/debian-lts-announce/2021/10/msg00010.html","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.usenix.org/conference/usenixsecurity21/presentation/kirzner","label":"af854a3a-2127-422b-91ae-364da2661108"}],"tags":["nvd","exploit-available"],"epss":0.00922,"epssPercentile":0.59147,"exploits":{"github":1,"githubRepos":["https://github.com/benschlueter/CVE-2021-33624"],"checkedAt":"2026-10-09T10:30:31.214Z"},"exploitAvailable":true,"ingestedAt":"2026-10-08T22:11:53.737Z","slug":"CVE-2021-33624","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `linux_kernel < 5.12.13`\n- `debian_linux = 9.0`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 5.12.13`","depth":"twilight","depthScore":38,"depthScoreParts":{"impact":25.9,"likelihood":0.2,"exploitation":12,"ransomware":0},"changes":[]}