CVE-2021-3490 Information

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 (pf: 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 (pf: Verifier do explicit ALU32 bounds tracking) (5.7-rc1) and the XOR variant was introduced by 2921c90d4718 (pf:Fix a verifier failure with xor) ( 5.10-rc1).

CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Reference

https://ubuntu.com/security/notices/USN-4949-1 https://www.zerodayinitiative.com/advisories/ZDI-21-606/ https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=049c4e13714ecbca567b4d5f6d563f05d431c80e https://ubuntu.com/security/notices/USN-4950-1 https://www.openwall.com/lists/oss-security/2021/05/11/11 https://security.netapp.com/advisory/ntap-20210716-0004/ http://packetstormsecurity.com/files/164015/Linux-eBPF-ALU32-32-bit-Invalid-Bounds-Tracking-Local-Privilege-Escalation.html

Attack Complexity

LOW

Privileges Required

LOW

User Interaction Required

LOW

Scope

NONE

Confidentiality Impact

UNCHANGED

Integrity Impact

HIGH

Availability Impact

HIGH

Base Score

HIGH

Base Severity

7.8