CVE-2021-47317
Description
A flaw was found in the Linux kernel's PowerPC Berkeley Packet Filter (BPF) Just-In-Time (JIT) compiler. When evaluating BPF programs, the verification check fails to examine the correct instruction field for certain atomic operations. A local user with permissions to load BPF programs could exploit this flaw by loading crafted programs, causing improper code compilation that results in a kernel hang and a Denial of Service (DoS).
Statement
This vulnerability is rated as Low severity because successful exploitation requires elevated local administrative privileges (CAP_BPF or CAP_SYS_ADMIN) on 64-bit PowerPC architectures to trigger a denial of service. By default, Red Hat Enterprise Linux disables unprivileged eBPF access, preventing standard users from loading BPF programs into the kernel. Consequently, the flaw cannot be triggered across other hardware platforms or by non-privileged accounts, limiting the blast radius to environments where authorized administrators execute non-standard atomic BPF instructions.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 4.4 | 3.3 | 7.8 |
| Attack Vector | Local | Local | Local |
| Attack Complexity | Low | Low | Low |
| Privileges Required | High | Low | Low |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | None | None | High |
| Integrity Impact | None | None | High |
| Availability Impact | High | Low | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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