CVE-2025-68726 in Linux
Summary
by MITRE • 12/24/2025
In the Linux kernel, the following vulnerability has been resolved:
crypto: aead - Fix reqsize handling
Commit afddce13ce81d ("crypto: api - Add reqsize to crypto_alg") introduced cra_reqsize field in crypto_alg struct to replace type specific reqsize fields. It looks like this was introduced specifically for ahash and acomp from the commit description as subsequent commits add necessary changes in these alg frameworks.
However, this is being recommended for use in all crypto algs instead of setting reqsize using crypto_*_set_reqsize(). Using cra_reqsize in aead algorithms, hence, causes memory corruptions and crashes as the underlying functions in the algorithm framework have not been updated to set the reqsize properly from cra_reqsize. [1]
Add proper set_reqsize calls in the aead init function to properly initialize reqsize for these algorithms in the framework.
[1]: https://gist.github.com/Pratham-T/24247446f1faf4b7843e4014d5089f6b
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Analysis
by VulDB Data Team • 12/28/2025
The vulnerability described in CVE-2025-68726 represents a critical memory corruption issue within the Linux kernel's cryptographic subsystem, specifically affecting the Advanced Encryption Standard (AES) and other Authenticated Encryption with Associated Data (AEAD) algorithms. This flaw stems from an improper implementation of the request size handling mechanism that was introduced in commit afddce13ce81d as part of the crypto API enhancement. The commit aimed to standardize the approach to request size management by introducing a unified cra_reqsize field within the crypto_alg structure, replacing the previous type-specific reqsize fields that were used primarily for hash algorithms and asynchronous crypto operations. However, this standardization effort was not properly extended to AEAD algorithms, creating a fundamental mismatch between the new framework design and the existing implementation.
The technical root cause of this vulnerability lies in the incomplete migration of AEAD algorithm implementations to utilize the new cra_reqsize field. When the crypto framework attempts to initialize AEAD algorithms, the underlying functions fail to properly set the request size from the newly introduced cra_reqsize field, leading to memory corruption and system crashes. This issue manifests because the AEAD algorithm initialization functions lack the necessary set_reqsize calls that would properly configure the request size parameters for these specific cryptographic operations. The vulnerability directly impacts the kernel's ability to safely process authenticated encryption requests, where the framework expects proper memory allocation and management for the cryptographic request structures. This flaw represents a classic case of incomplete code refactoring that creates a mismatch between the new API design and legacy implementation patterns, resulting in undefined behavior when cryptographic operations are executed.
The operational impact of this vulnerability is severe and potentially exploitable by malicious actors who can trigger the affected cryptographic operations through various kernel interfaces. System stability is at risk as the memory corruption can lead to kernel crashes, system panics, or more insidiously, allow for privilege escalation attacks that could compromise the entire system. The vulnerability affects any system running the affected Linux kernel version that processes AEAD cryptographic operations, which are commonly used in network protocols, disk encryption, and secure communication channels. Attackers could potentially exploit this vulnerability by crafting malicious inputs that trigger the affected cryptographic algorithms, leading to denial of service conditions or unauthorized access to system resources. The nature of the flaw means that even legitimate cryptographic operations could cause system instability, making this vulnerability particularly dangerous in production environments where cryptographic services are heavily utilized.
Mitigation strategies for this vulnerability require immediate kernel updates that include the proper set_reqsize calls in the AEAD algorithm initialization functions, ensuring that the cra_reqsize field is correctly utilized throughout the cryptographic framework. System administrators should prioritize applying the patched kernel version that resolves this issue by properly implementing the required initialization logic for AEAD algorithms. Additionally, monitoring systems should be configured to detect unusual cryptographic operation patterns that might indicate exploitation attempts. The fix addresses the core issue by ensuring that all cryptographic algorithms properly initialize their request size parameters according to the new framework standards, preventing the memory corruption that occurs when the framework attempts to access improperly configured request structures. This vulnerability aligns with CWE-122 (Heap Overflow) and CWE-787 (Out-of-bounds Write) categories, and could potentially map to ATT&CK techniques involving privilege escalation and system instability through kernel exploitation. Organizations should implement comprehensive patch management procedures to ensure all systems receive the necessary updates and should consider deploying additional security monitoring to detect potential exploitation attempts targeting this specific kernel vulnerability.