{"id":"CVE-2021-3490","url":"https://www.cyber-defence.io/tools/cve/CVE-2021-3490","generatedAt":"2026-11-05T01:17:38.028Z","title":"The eBPF ALU32 bounds tracking for bitwise ops (AND, OR and XOR) in the Linux kernel did not properly update 32-bit bounds, which could be turned into out of bounds reads and writes in the Linux kernel and therefore, arbitrary code execution.","description":"The eBPF ALU32 bounds tracking for bitwise ops (AND, OR and XOR) in the Linux kernel did not properly update 32-bit bounds, which could be turned into out of bounds reads and writes in the Linux kernel and therefore, arbitrary code execution. This issue was fixed via commit 049c4e13714e (\"bpf: Fix alu32 const subreg bound tracking on bitwise operations\") (v5.13-rc4) and backported to the stable kernels in v5.12.4, v5.11.21, and v5.10.37. The AND/OR issues were introduced by commit 3f50f132d840 (\"bpf: Verifier, do explicit ALU32 bounds tracking\") (5.7-rc1) and the XOR variant was introduced by 2921c90d4718 (\"bpf:Fix a verifier failure with xor\") ( 5.10-rc1).","published":"2021-06-04T02:15:07.000Z","lastModified":"2026-06-17T04:05:12.000Z","status":"Modified","sourceIdentifier":"security@ubuntu.com","cvss":{"version":"3.1","score":7.8,"severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"},"cwe":["CWE-20","CWE-787","CWE-125"],"affected":["linux/linux kernel","canonical/ubuntu linux"],"epss":{"score":0.27381,"percentile":0.98067,"date":"2026-11-03","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"urgent","text":"EPSS puts the probability of exploitation in the next 30 days at 27.4%, higher than 98% of all known CVEs. Patch or mitigate before the next change window."},"changes":[],"references":[{"url":"http://packetstormsecurity.com/files/164015/Linux-eBPF-ALU32-32-bit-Invalid-Bounds-Tracking-Local-Privilege-Escalation.html","tags":["Exploit","Third Party Advisory","VDB Entry"],"source":"security@ubuntu.com"},{"url":"https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=049c4e13714ecbca567b4d5f6d563f05d431c80e","tags":["Patch","Vendor Advisory"],"source":"security@ubuntu.com"},{"url":"https://security.netapp.com/advisory/ntap-20210716-0004/","tags":["Third Party Advisory"],"source":"security@ubuntu.com"},{"url":"https://ubuntu.com/security/notices/USN-4949-1","tags":["Third Party Advisory"],"source":"security@ubuntu.com"},{"url":"https://ubuntu.com/security/notices/USN-4950-1","tags":["Third Party Advisory"],"source":"security@ubuntu.com"},{"url":"https://www.openwall.com/lists/oss-security/2021/05/11/11","tags":["Mailing List","Patch","Third Party Advisory"],"source":"security@ubuntu.com"},{"url":"https://www.zerodayinitiative.com/advisories/ZDI-21-606/","tags":["Third Party Advisory","VDB Entry"],"source":"security@ubuntu.com"},{"url":"http://packetstormsecurity.com/files/164015/Linux-eBPF-ALU32-32-bit-Invalid-Bounds-Tracking-Local-Privilege-Escalation.html","tags":["Exploit","Third Party Advisory","VDB Entry"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=049c4e13714ecbca567b4d5f6d563f05d431c80e","tags":["Patch","Vendor Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://security.netapp.com/advisory/ntap-20210716-0004/","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://ubuntu.com/security/notices/USN-4949-1","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://ubuntu.com/security/notices/USN-4950-1","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.openwall.com/lists/oss-security/2021/05/11/11","tags":["Mailing List","Patch","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.zerodayinitiative.com/advisories/ZDI-21-606/","tags":["Third Party Advisory","VDB Entry"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2021-3490","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}