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Date: Tue, 27 Oct 2020 13:23:01 +0530
From: Huzaifa Sidhpurwala <>
Subject: CVE-2020-25654 pacemaker: ACL restrictions bypass

Hi All,

Pacemaker is a high-availability cluster manager comprising multiple
daemon processes that interact with each other and with user requests
via IPC.

Users must either be root or in the haclient group to access Pacemaker
daemon IPC.

One of these daemons, pacemaker-based, manages the Pacemaker
configuration, known as the Cluster Information Base (CIB). Pacemaker
may be built with support for Access Control Lists (ACLs) in which case
pacemaker-based applies configured ACLs when processing user requests to
read or write any part of the configuration.

When ACLs are not in use, any user in the haclient group has full
access to the configuration, which effectively gives them the ability
to run any code as root. (This is intentional, as the point of a
cluster manager is to run arbitrary services.)

When ACLs are in use, users still must be in the haclient group, but
their read and write access to various parts of the configuration is
limited by configured ACLs.

The vulnerability is that users may use IPC communication with the
various daemons directly to perform certain tasks that they would be
prevented by ACLs from doing if they went through the configuration.
This is not difficult; Pacemaker provides command-line tools to send
many types of IPC requests.

More details along with patches is available at:

Huzaifa Sidhpurwala / Red Hat Product Security

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