CVE-2019-14865 in grub2
Summary
by MITRE
A flaw was found in the grub2-set-bootflag utility of grub2. A local attacker could run this utility under resource pressure (for example by setting RLIMIT), causing grub2 configuration files to be truncated and leaving the system unbootable on subsequent reboots.
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Analysis
by VulDB Data Team • 04/29/2025
The vulnerability identified as CVE-2019-14865 resides within the grub2-set-bootflag utility component of the GRand Unified Bootloader version 2 system. This flaw represents a critical security weakness that manifests when the utility operates under constrained resource conditions, particularly when subjected to resource limit restrictions such as those imposed through the RLIMIT system call. The issue stems from inadequate error handling and resource management within the utility's file manipulation processes, creating a scenario where system stability and boot integrity become compromised. The vulnerability is classified under CWE-122, which addresses buffer overflow conditions, and specifically relates to improper handling of resource constraints during file operations. The GRUB2 bootloader serves as a fundamental component in Linux system initialization, making this vulnerability particularly dangerous as it directly impacts system bootability and overall operational integrity.
The technical mechanism behind this vulnerability involves the grub2-set-bootflag utility's failure to properly manage file I/O operations when resource limits are imposed on the executing process. When an attacker deliberately sets restrictive resource limits using RLIMIT parameters, the utility encounters resource exhaustion conditions during its configuration file modification process. This resource pressure causes the utility to prematurely terminate file write operations, resulting in partial or complete truncation of the grub2 configuration files. The truncation occurs at critical points in the file writing sequence, leaving the configuration files in an inconsistent state that prevents proper system booting. The flaw operates at the intersection of process resource management and file system integrity, where the utility lacks proper error recovery mechanisms to handle interrupted I/O operations under constrained conditions. This behavior aligns with ATT&CK technique T1490, which covers data destruction through manipulation of system boot processes.
The operational impact of CVE-2019-14865 extends beyond simple denial of service, creating a persistent threat to system availability and recovery capabilities. A local attacker with minimal privileges can exploit this vulnerability to render systems unbootable, effectively creating a persistent denial of service condition that requires manual intervention to resolve. The consequences include complete system outages requiring physical access or remote recovery procedures to restore normal operation. Organizations relying on automated systems or those with critical uptime requirements face significant operational risks, as the vulnerability can be exploited without requiring elevated privileges or network access. The impact is particularly severe in environments where system administrators cannot easily access physical hardware or where automated recovery mechanisms depend on proper bootloader configuration. The vulnerability's exploitation directly contradicts the principle of system resilience and can cause cascading failures in networked environments where multiple systems depend on consistent boot behavior. This flaw represents a serious threat to enterprise infrastructure stability and can result in extended downtime costs and potential data loss scenarios.
Mitigation strategies for CVE-2019-14865 should focus on both immediate system hardening and long-term architectural improvements. System administrators should ensure that all affected GRUB2 installations are updated to versions that contain proper resource handling and error recovery mechanisms. The implementation of proper file system integrity checks and backup procedures for grub2 configuration files provides essential protection against exploitation. Organizations should also implement monitoring solutions that can detect abnormal file modification patterns or resource limit configurations that might indicate attempted exploitation. Process isolation and resource management policies should be strengthened to prevent unauthorized manipulation of system utilities under resource constraint conditions. The vulnerability highlights the importance of robust error handling in system utilities and emphasizes the need for comprehensive testing under various resource conditions. Security teams should consider implementing automated patch management processes specifically targeting bootloader components to prevent similar vulnerabilities from remaining unaddressed. Additionally, regular system audits should verify that grub2 configuration files maintain proper integrity and that no unauthorized modifications have occurred, providing early detection capabilities for potential exploitation attempts.