SB20261022404 - Fedora 43 update for util-linux
Published: October 22, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 2 vulnerabilities.
1) Race condition (CVE-ID: CVE-2026-27456)
CWE-ID: CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
CVSSv4: 8.2 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N]
The vulnerability allows a local user to gain access to sensitive information.
The vulnerability exists due to a race condition in the SUID binary /usr/bin/mount from util-linux. A local user can mount any root-owned file or block device that contains a valid filesystem, gaining full read access to its contents.
The mounted filesystem has MS_SECURE flags applied (nosuid, nodev, noexec), which prevents execution of SUID binaries but does not restrict reading data.
2) Detection of Error Condition Without Action (CVE-ID: CVE-2026-76642)
CWE-ID: CWE-390 - Detection of error condition without action
CVSSv4: 8.5 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a local user to escalate privileges.
The vulnerability exists due to incorrect status handling in libmount post-mount hooks when processing a failed external mount helper. A local user can trigger a nonzero helper exit for a root-controlled fstab entry with X-mount.idmap to escalate privileges.
Exploitation requires SUID-root mount(8), a usable root-controlled fstab entry, a failed external mount helper, and an idmap-capable filesystem target.
Remediation
Install update from vendor's website.