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redhatcveRedhat.comRH:CVE-2021-35477
HistoryAug 02, 2021 - 4:50 p.m.

CVE-2021-35477

2021-08-0216:50:02
redhat.com
access.redhat.com
47

5.5 Medium

CVSS3

Attack Vector

LOCAL

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

NONE

Availability Impact

NONE

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

2.1 Low

CVSS2

Access Vector

LOCAL

Access Complexity

LOW

Authentication

NONE

Confidentiality Impact

PARTIAL

Integrity Impact

NONE

Availability Impact

NONE

AV:L/AC:L/Au:N/C:P/I:N/A:N

0.0005 Low

EPSS

Percentile

13.7%

A flaw in the Linux kernel allows a privileged BPF program to obtain sensitive information from kernel memory via a Speculative Store Bypass side-channel in the eBPF subsystem

Mitigation

The default Red Hat Enterprise Linux kernel setting prevents unprivileged users from being able to use eBPF via the kernel.unprivileged_bpf_disabled sysctl. As such, exploiting this issue would require a privileged user with CAP_SYS_ADMIN or root.

For the Red Hat Enterprise Linux 7 the eBPF for unprivileged users is always disabled. For the Red Hat Enterprise Linux 8 to confirm the current state, inspect the sysctl with the command:

cat /proc/sys/kernel/unprivileged_bpf_disabled

The setting of 1 (default) would mean that unprivileged users cannot use eBPF. Otherwise, to disable eBPF for unprivileged users, add:

kernel.unprivileged_bpf_disabled = 1

To the file "/etc/sysctl.d/disable-ebpf.conf"

Then running the following command as root:

sudo sysctl --system

5.5 Medium

CVSS3

Attack Vector

LOCAL

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

NONE

Availability Impact

NONE

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

2.1 Low

CVSS2

Access Vector

LOCAL

Access Complexity

LOW

Authentication

NONE

Confidentiality Impact

PARTIAL

Integrity Impact

NONE

Availability Impact

NONE

AV:L/AC:L/Au:N/C:P/I:N/A:N

0.0005 Low

EPSS

Percentile

13.7%

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