CVE-2026-21387 in LLM Library for PyTorch
Summary
by MITRE • 08/12/2026
Protection mechanism failure for some Intel(R) LLM Library for PyTorch within Ring 3: User Applications may allow an escalation of privilege. Unprivileged software adversary with a privileged user combined with a low complexity attack may enable escalation of privilege. This result may potentially occur via local access when attack requirements are present without special internal knowledge and requires passive user interaction. The potential vulnerability may impact the confidentiality (high), integrity (high) and availability (high) of the vulnerable system, resulting in subsequent system confidentiality (none), integrity (none) and availability (none) impacts.
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Analysis
by VulDB Data Team • 08/12/2026
This vulnerability represents a critical privilege escalation flaw within Intel's Large Language Model library for PyTorch, specifically affecting systems operating in Ring 3 user application contexts. The protection mechanism failure occurs when unprivileged software adversaries leverage legitimate privileged user accounts to execute malicious code that bypasses normal security boundaries. This weakness stems from inadequate isolation controls between user-space applications and system-level privileges, creating a pathway for attackers to elevate their access rights without requiring additional authorization mechanisms. The vulnerability's classification as low complexity attack requirement means that adversaries can exploit this flaw with minimal technical sophistication, while the passive user interaction component suggests that users may unknowingly trigger the privilege escalation during normal application usage patterns.
The technical implementation of this vulnerability involves flaws in how Intel's LLM library manages memory access controls and privilege boundaries within PyTorch applications. When legitimate privileged users execute applications that utilize this library, the system fails to properly validate or restrict the elevated privileges being granted to user-space processes. This failure creates opportunities for malicious code injection or manipulation of system calls that should normally be restricted to kernel-level operations. The vulnerability operates through a combination of memory corruption techniques and privilege boundary violations that allow attackers to manipulate system resources while maintaining the appearance of legitimate user activity. According to CWE classification, this represents a weakness in privilege management where insufficient checks lead to unauthorized privilege escalation, specifically aligning with CWE-276 for improper privileges and CWE-782 for exposed privilege escalation.
The operational impact of this vulnerability extends across all three fundamental security principles with high severity implications for confidentiality, integrity, and availability. Systems compromised through this vulnerability could experience complete data exposure where confidential information becomes accessible to unauthorized parties due to the elevated privileges gained. The integrity of system operations becomes critically compromised as attackers can modify system files, alter application behavior, or manipulate core system functions without detection. Availability is simultaneously threatened as malicious actors can potentially disrupt system services or cause denial-of-service conditions through privilege escalation attacks. From an attack perspective, this vulnerability aligns with several ATT&CK tactics including privilege escalation and defense evasion techniques, where adversaries leverage legitimate administrative privileges to maintain persistent access while avoiding security monitoring systems.
Mitigation strategies should focus on immediate patch deployment from Intel to address the underlying library implementation flaws, combined with network segmentation to limit the attack surface available to potential adversaries. System administrators should implement strict application whitelisting policies that prevent unauthorized execution of potentially vulnerable PyTorch applications, while also monitoring for unusual privilege escalation patterns in system logs. Additional protective measures include disabling unnecessary user privileges where possible, implementing robust process monitoring to detect anomalous behavior, and maintaining regular security audits of all installed libraries and frameworks. The vulnerability's requirement for local access and passive user interaction suggests that endpoint protection solutions should be enhanced with behavioral analysis capabilities to identify suspicious privilege escalation attempts. Organizations should also consider implementing zero-trust network principles where no user or application is trusted by default, requiring continuous verification of privileges and system integrity checks to prevent exploitation of this type of protection mechanism failure.