CVE-2026-19411 in Shim
Summary
by MITRE • 08/11/2026
A NULL pointer vulnerability has been found in the the shim application of dp.c library. A missing NULL pointer could allow attackers to perform a denial of service attack on a system that uses shim application for UEFI bootloader.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 08/11/2026
The vulnerability under examination represents a critical null pointer dereference flaw within the shim application component of the dp.c library, a fundamental element in UEFI bootloader implementations. This security weakness exists in the shim application which serves as a crucial intermediary layer between the UEFI firmware and the operating system boot process. The shim acts as a trusted bootloader that verifies and loads subsequent boot components while maintaining secure boot chain integrity.
The technical flaw manifests when the dp.c library fails to properly validate pointer references during the bootloader execution phase, creating an avenue for null pointer dereference conditions. This occurs specifically within the shim application's handling of UEFI device path structures where the code does not adequately check for NULL return values from memory allocation functions or device path manipulation routines. When legitimate boot sequences encounter malformed or unexpected device path configurations, the application attempts to access a NULL pointer, resulting in immediate system termination and complete denial of service.
The operational impact of this vulnerability extends beyond simple service interruption as it fundamentally undermines system availability and integrity within UEFI environments. Attackers can exploit this weakness by crafting malicious device path entries or manipulating boot configuration parameters that trigger the null pointer condition during shim execution. The consequences include complete system lockdown where legitimate boot operations fail, rendering affected systems unusable until manual intervention occurs through recovery mechanisms or firmware updates. This vulnerability particularly affects enterprise and embedded systems where UEFI secure boot is enabled and critical infrastructure relies on proper bootloader functionality.
Mitigation strategies should focus on immediate patch deployment addressing the null pointer validation issue within the shim application's dp.c library implementation. Organizations must prioritize updating their UEFI firmware and bootloader components to versions that include proper NULL pointer checks and error handling routines. Security teams should implement monitoring for unusual boot behavior patterns and establish robust recovery procedures including manual boot restoration capabilities. The vulnerability aligns with CWE-476 which specifically addresses null pointer dereference conditions, and represents a potential ATT&CK technique under T1499 which encompasses network disruption and system resource consumption attacks through denial of service mechanisms.
The broader implications for system security highlight the critical importance of proper input validation and error handling in low-level bootloader components. This vulnerability demonstrates how seemingly minor code oversight in trusted boot components can create severe availability risks that affect entire system infrastructure. Regular security assessments of UEFI firmware components and comprehensive testing of device path handling routines should become standard practices to prevent similar issues from emerging in production environments, particularly given the widespread adoption of secure boot technologies across enterprise and government systems that rely on consistent shim application behavior for proper system initialization.