CVE-2026-18938 in Red Hat
Summary
by MITRE • 08/07/2026
A flaw was found in p11-kit. A local attacker, or one with equivalent access to a reachable RPC channel, could exploit an integer overflow vulnerability. By sending specially crafted messages, the attacker can cause the system to miscalculate memory allocation for nested attributes. This leads to a memory corruption issue, specifically a heap out-of-bounds write, which can crash the p11-kit RPC parsing process, resulting in a Denial of Service (DoS). This vulnerability is only exploitable on 32 bit systems.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 08/07/2026
The p11-kit library serves as a crucial component in cryptographic infrastructure, providing a standardized interface for accessing hardware security modules and cryptographic services through the PKCS#11 standard. This library facilitates secure communication between applications and cryptographic tokens, making it a fundamental element in enterprise security architectures. When vulnerabilities exist within such core components, they can have widespread implications across systems that rely on PKCS#11 compliance for their cryptographic operations. The integer overflow vulnerability discovered in p11-kit represents a particularly concerning flaw due to its potential for remote exploitation and the critical nature of the affected system components.
The technical implementation of this vulnerability stems from improper handling of integer values during memory allocation calculations within the RPC parsing functionality of p11-kit. When processing nested attributes through the remote procedure call interface, the system performs arithmetic operations that can exceed the maximum representable value for 32-bit signed integers. This overflow condition causes subsequent memory allocation calculations to produce incorrect values, leading to heap-based buffer overflows where the application attempts to write data beyond allocated memory boundaries. The specific nature of this vulnerability aligns with CWE-190, which catalogs integer overflow conditions that can result in memory corruption and arbitrary code execution. The flaw manifests as a heap out-of-bounds write operation that directly compromises the integrity of the application's memory management system.
The operational impact of this vulnerability extends beyond simple service disruption, creating potential pathways for more sophisticated attacks within environments where p11-kit is deployed. A local attacker with access to the RPC channel can leverage this weakness to trigger immediate process termination through controlled memory corruption, effectively executing a denial of service attack against critical cryptographic services. The DoS condition specifically targets the p11-kit RPC parsing process, which serves as a bridge between applications and hardware security modules, potentially disrupting authentication workflows, certificate management operations, and secure key storage functions. This vulnerability's exploitation requires minimal privileges relative to other system components, making it particularly dangerous in multi-tenant environments where isolation between processes may be compromised. The attack vector through RPC channels represents a significant concern for enterprise deployments where network exposure is common.
The limited scope of this vulnerability to 32-bit systems provides some mitigation context while also highlighting the importance of system architecture considerations in security planning. This architectural constraint means that 64-bit deployments remain unaffected, but organizations with mixed environments must carefully evaluate their attack surface. The vulnerability demonstrates how legacy system architectures can harbor critical flaws even in well-established software components, emphasizing the need for continuous security assessment across all deployed platforms. Organizations should implement immediate patching strategies and consider network segmentation to limit potential RPC channel exposure while maintaining comprehensive monitoring of cryptographic service availability. The ATT&CK framework's technique T1499.004 for network denial of service highlights how such vulnerabilities can be weaponized in coordinated attack campaigns targeting infrastructure components that rely on cryptographic services.
Mitigation strategies should prioritize immediate deployment of patched versions of p11-kit while implementing network-level controls to restrict RPC channel access to trusted entities only. System administrators should establish monitoring protocols to detect anomalous memory allocation patterns and process termination events that may indicate exploitation attempts. The implementation of privilege separation mechanisms and mandatory access controls can reduce the potential impact of successful exploitation attempts, even though the vulnerability itself is limited in its execution scope. Organizations should also conduct comprehensive inventory assessments to identify all systems utilizing p11-kit RPC functionality and ensure consistent patch management across their cryptographic infrastructure components. Long-term security planning should include architectural reviews that consider migrating away from vulnerable 32-bit deployments where possible, while maintaining awareness of similar integer overflow patterns in other cryptographic libraries and system components.