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redhatcveRedhat.comRH:CVE-2021-3715
HistorySep 07, 2021 - 8:38 a.m.

CVE-2021-3715

2021-09-0708:38:09
redhat.com
access.redhat.com
64

7.8 High

CVSS3

Attack Vector

LOCAL

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

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

7.2 High

CVSS2

Access Vector

Access Complexity

Authentication

NONE

Confidentiality Impact

COMPLETE

Integrity Impact

COMPLETE

Availability Impact

COMPLETE

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

0.0004 Low

EPSS

Percentile

5.1%

A flaw was found in the β€œRouting decision” classifier in the Linux kernel’s Traffic Control networking subsystem in the way it handled changing of classification filters, leading to a use-after-free condition. This flaw allows unprivileged local users to escalate their privileges on the system. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.

Mitigation

In order to mitigate this issue, it is possible to prevent the affected code from being loaded by blacklisting the kernel module cls_route.ko. For instructions relating to how to blacklist a kernel module refer to: <https://access.redhat.com/solutions/41278&gt;.

Alternatively, if cls_route is being used, on Red Hat Enterprise Linux 8, you can disable unprivileged user namespaces by setting user.max_user_namespaces to 0:

echo "user.max_user_namespaces=0" > /etc/sysctl.d/userns.conf

sysctl -p /etc/sysctl.d/userns.conf

7.8 High

CVSS3

Attack Vector

LOCAL

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

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

7.2 High

CVSS2

Access Vector

Access Complexity

Authentication

NONE

Confidentiality Impact

COMPLETE

Integrity Impact

COMPLETE

Availability Impact

COMPLETE

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

0.0004 Low

EPSS

Percentile

5.1%