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CVE-2021-3490

Public on 2021-06-04
Modified on 2024-03-01
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).

Severity
Medium
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CVSS v3 Base Score
7.8
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Affected Packages

Platform Package Release Date Advisory
Amazon Linux 2 - Kernel-5.10 Extra kernel 2022-01-20 23:18 ALAS2KERNEL-5.10-2022-001
Amazon Linux 2 - Kernel-5.10 Extra kernel 2022-01-20 23:37 ALAS2KERNEL-5.10-2022-002

CVSS Scores

Score Type Score Vector
Amazon Linux CVSSv3 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD CVSSv2 7.2 AV:L/AC:L/Au:N/C:C/I:C/A:C
NVD CVSSv3 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

References

Red Hat: CVE-2021-3490 Mitre: CVE-2021-3490 FAQs regarding Amazon Linux ALAS/CVE Severity