CVE-2022-48831 in Linux
Summary
by MITRE • 07/16/2024
In the Linux kernel, the following vulnerability has been resolved:
ima: fix reference leak in asymmetric_verify()
Don't leak a reference to the key if its algorithm is unknown.
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Analysis
by VulDB Data Team • 09/25/2025
The vulnerability identified as CVE-2022-48831 represents a reference leak in the Linux kernel's Integrity Measurement Architecture (IMA) subsystem, specifically within the asymmetric_verify() function. This issue occurs when the kernel attempts to verify asymmetric signatures but encounters a key algorithm that is not recognized or supported by the system. The IMA framework serves as a critical component for ensuring system integrity by measuring and validating the integrity of files and kernel modules, making this vulnerability particularly concerning for security-conscious environments. The flaw manifests when the kernel fails to properly release a reference to a cryptographic key object, leading to potential resource exhaustion and system instability. This type of memory management issue falls under the category of resource leak vulnerabilities that can be exploited to consume system resources over time, ultimately impacting system performance and availability.
The technical root cause of this vulnerability lies in the asymmetric_verify() function's handling of cryptographic key references within the IMA subsystem. When processing asymmetric signature verification requests, the kernel checks the key algorithm to determine how to properly validate the signature. However, when an unknown or unsupported algorithm is encountered, the function fails to properly decrement the reference count of the key object before returning from the function. This creates a dangling reference that prevents the kernel's memory management system from properly freeing the associated key structure. The vulnerability is classified as a reference counting error that violates proper resource management practices, aligning with CWE-466 which addresses improper handling of reference counting mechanisms. The flaw demonstrates a classic example of how insufficient error handling in cryptographic operations can lead to resource leaks that may be exploited by malicious actors to perform resource exhaustion attacks.
The operational impact of CVE-2022-48831 extends beyond simple resource consumption, potentially affecting system stability and availability in production environments. In high-traffic systems where IMA is actively measuring and verifying files, repeated occurrences of this reference leak could lead to progressive memory consumption, eventually causing system slowdowns or even kernel oops situations. The vulnerability is particularly dangerous in environments where IMA is configured to enforce strict integrity policies, as malicious actors could potentially craft specially crafted files or modules designed to trigger this specific code path repeatedly. Attackers could exploit this vulnerability through various means including uploading malicious files that contain invalid cryptographic signatures or manipulating system processes that rely on IMA verification. The impact is further amplified when considering that IMA is often used in security-critical applications such as secure boot processes, containerized environments, and compliance monitoring systems where system stability is paramount.
Mitigation strategies for CVE-2022-48831 focus primarily on applying the kernel patch that resolves the reference leak in the asymmetric_verify() function. System administrators should prioritize updating their Linux kernel installations to versions that include the fix, typically found in kernel releases 5.19 and later. The patch ensures that when an unknown algorithm is encountered during signature verification, the kernel properly releases the reference to the key object before returning from the function. Organizations should implement comprehensive patch management procedures that include testing the updated kernel in non-production environments before deployment to ensure compatibility with existing security policies and system configurations. Additional monitoring should be implemented to track memory usage patterns and identify potential resource exhaustion symptoms that might indicate exploitation attempts. Security teams should also review their IMA configuration settings to ensure they are not inadvertently exposing systems to unnecessary risk through overly permissive integrity policies. The fix aligns with ATT&CK technique T1553.006 for bypassing signature validation, as it prevents an attacker from leveraging the reference leak to maintain persistent access or escalate privileges through system integrity mechanisms. Regular security audits of kernel components and cryptographic subsystems should be conducted to identify similar reference counting issues that may exist in other parts of the kernel codebase.