CVE-2026-59676 in SELinux
Summary
by MITRE • 07/23/2026
A Time-of-check Time-of-use (TOCTOU) Race Condition vulnerability in seunshare of selinux policycoreutils allows a user calling seunshare that is running in the unconfined SELinux domain to delete arbitrary root-owned files,
This issue affects policycoreutils through 3.10.
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Analysis
by VulDB Data Team • 07/24/2026
The Time-of-check Time-of-use race condition vulnerability in seunshare represents a critical security flaw within the selinux policycoreutils package that enables privilege escalation and unauthorized file deletion. This vulnerability specifically targets users operating within the unconfined SELinux domain who execute the seunshare command, creating a dangerous scenario where malicious actors can leverage temporal inconsistencies in access control checks to perform actions beyond their intended permissions.
The technical flaw manifests through a classic race condition pattern where the system performs an access check at one point in time and then executes the operation at a later point when conditions may have changed. In this case, seunshare conducts a permission check before performing file operations but fails to maintain consistent state validation between the check and execution phases. The vulnerability stems from the fact that during the brief window between the time-of-check and time-of-use, an attacker can manipulate the filesystem or change file ownership, allowing deletion of root-owned files that would normally be protected by SELinux policies.
This race condition creates a significant operational impact as it allows users in the unconfined domain to bypass normal security boundaries and delete critical system files. The vulnerability affects all versions of policycoreutils up to and including version 3.10, making it a widespread concern across numerous Linux distributions that rely on SELinux for mandatory access control. Attackers can exploit this flaw to remove essential system components, potentially leading to system instability, complete compromise, or denial of service conditions.
The vulnerability directly maps to CWE-367, which defines Time-of-Check to Time-of-Use (TOCTOU) race conditions as a well-known weakness in software security. From an ATT&CK perspective, this represents a privilege escalation technique under T1068, where adversaries leverage weaknesses in access control mechanisms to gain elevated privileges. The issue also relates to T1548.001 which covers abuse of Sudo or similar privilege escalation tools, though in this case the escalation occurs through SELinux policy enforcement rather than traditional sudo mechanisms.
Mitigation strategies should focus on immediate package updates to versions that address the race condition, ensuring proper synchronization between access checks and file operations. System administrators should also implement restrictive SELinux policies that limit execution of seunshare to only trusted users and processes. Additionally, monitoring for unauthorized execution of seunshare and implementing file integrity monitoring solutions can help detect exploitation attempts. The most effective long-term solution involves patching the affected policycoreutils package to eliminate the temporal inconsistency in access control validation.
The vulnerability demonstrates how seemingly minor implementation flaws in security tools can create significant attack vectors within complex security frameworks like SELinux. It highlights the importance of rigorous testing for race conditions in security-critical code paths and underscores the need for comprehensive security reviews of privilege escalation mechanisms. Organizations should prioritize updating their systems to patched versions while implementing additional monitoring controls to detect potential exploitation attempts targeting this specific vulnerability pattern.