CVE-2026-78237 in ABR
Summary
by MITRE • 08/26/2026
Insufficient input validation in ABR allows a low-privileged user to inject malicious entries into the sudoers file, resulting in persistent root access that remained effective after the ABR session ended.
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Analysis
by VulDB Data Team • 08/26/2026
The vulnerability described constitutes a critical privilege escalation flaw within the Access Broker or Administrative Boundary Resolution (ABR) system, stemming from insufficient input validation mechanisms during user authentication and authorization processes. This defect allows an attacker with low-privileged access to manipulate internal configuration files, specifically targeting the sudoers file which governs command execution privileges on Unix-like operating systems. By injecting malicious entries into this file, the attacker effectively bypasses standard security controls that restrict administrative actions to authorized personnel only. The core technical flaw lies in the failure of the ABR system to properly sanitize or validate user-supplied data before it is processed and written to sensitive configuration files. This lack of rigorous input validation creates a pathway for code injection or command execution under elevated privileges, fundamentally undermining the principle of least privilege that should govern such systems.
From an operational perspective, this vulnerability enables persistent root access, which represents one of the most severe outcomes in cybersecurity incidents. Unlike temporary session-based exploits where elevation is lost upon logout, the modification of the sudoers file ensures that the malicious entries remain active even after the initial ABR session concludes. This persistence allows the attacker to maintain long-term control over the compromised system without needing to re-exploit the vulnerability repeatedly. The ability to execute commands with root privileges grants full control over the operating system, including the capability to install backdoors, exfiltrate sensitive data, modify security policies, and pivot to other systems within the network infrastructure. This level of access effectively neutralizes most defensive measures that rely on user-level restrictions for protection.
The technical implications align closely with CWE-78 Improper Neutralization of Special Elements used in an OS Command (OS Command Injection) and CWE-269 Improvement of Privilege, as the attacker leverages a low-privileged account to gain high-privilege access through flawed input handling. Furthermore, this behavior is consistent with MITRE ATT&CK technique T1548 Abuse Elevation Control Mechanism, where adversaries exploit misconfigurations or flaws in operating system elevation controls to escalate privileges. The persistence aspect also relates to techniques such as T1098 Account Manipulation, specifically the modification of authentication mechanisms or configuration files to maintain access. These mappings highlight how the vulnerability fits into broader threat actor methodologies for establishing and maintaining footholds within enterprise environments.
Mitigation strategies must focus on implementing strict input validation and output encoding practices throughout the ABR application lifecycle. Developers should ensure that all user inputs are validated against a whitelist of expected values rather than relying solely on blacklist approaches, which can be bypassed through obfuscation or edge cases. Additionally, principle of least privilege should be enforced by restricting write access to critical system files like sudoers to only those processes and users that absolutely require it. Implementing file integrity monitoring solutions such as AIDE or Tripwire can help detect unauthorized modifications to configuration files in real-time. Regular security audits and penetration testing focused on authentication modules are essential to identify similar flaws before they can be exploited by malicious actors.