CVE-2026-84828 Pcs: pcs: non-root haclient users can read arbitrary files via pcs host auth --token

Description

A flaw was found in PCS (Pacemaker Configuration System). A local attacker with membership in the 'haclient' group can exploit the 'pcs host auth --token' command to read the contents of arbitrary files on the filesystem, provided the files are shorter than 256 bytes. The file contents are read with root privileges by the pcsd daemon and can be exfiltrated by the attacker through subsequent cluster node communication. This allows disclosure of sensitive data such as API keys, tokens, or configuration secrets that would otherwise be inaccessible to the attacker.

Exploitable with local access to the machine, with an ordinary account and without any user action; an attacker can seriously compromise confidentiality, integrity or availability.

Attack vector

Local

Attack complexity

Low

Privileges required

Low

Interaction

None

Scope

Changed

Confidentiality

High

Integrity

None

Availability

None

Affected products and versions