Symlink traversal privilege escalation via libacl functions

Summary

acl before version 2.4.0 contains a symlink traversal vulnerability in the libacl pathname-based functions acl_get_file(), acl_set_file(), acl_extended_file(), and acl_delete_def_file() that allows local attackers to escalate privileges by replacing any pathname component with a symbolic link. Attackers who control any component of a pathname processed by a privileged caller can redirect ACL read or write operations to arbitrary files or directories, enabling unauthorized manipulation of access control lists and local privilege escalation. A flaw was found in the `acl` package, specifically within its `libacl` pathname-based functions. A local attacker could exploit this vulnerability by using a symbolic link to replace a pathname component. This could allow the attacker to redirect access control list (ACL) read or write operations to arbitrary files or directories, leading to unauthorized manipulation of ACLs and ultimately local privilege escalation. Red Hat severity: Important — CVSS 7.1 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N). Weakness: CWE-59. Fixed by RHSA-2026:34351 — update the affected packages (`sudo dnf update`). Affected Red Hat products: Red Hat Hardened Images.