CVE-2025-68724 in Linux
Summary
by MITRE • 12/24/2025
In the Linux kernel, the following vulnerability has been resolved:
crypto: asymmetric_keys - prevent overflow in asymmetric_key_generate_id
Use check_add_overflow() to guard against potential integer overflows when adding the binary blob lengths and the size of an asymmetric_key_id structure and return ERR_PTR(-EOVERFLOW) accordingly. This prevents a possible buffer overflow when copying data from potentially malicious X.509 certificate fields that can be arbitrarily large, such as ASN.1 INTEGER serial numbers, issuer names, etc.
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Analysis
by VulDB Data Team • 01/12/2026
The vulnerability identified as CVE-2025-68724 resides within the Linux kernel's asymmetric key handling subsystem, specifically in the crypto framework's implementation of asymmetric key identification. This flaw represents a critical integer overflow condition that could potentially lead to buffer overflow scenarios when processing X.509 certificate data. The vulnerability manifests in the asymmetric_key_generate_id function where the kernel attempts to calculate the total size required for storing key identifiers by summing various binary blob lengths with the size of the asymmetric_key_id structure. The absence of proper overflow checking in this calculation creates a pathway for maliciously crafted certificate fields to trigger arithmetic overflow conditions that could compromise memory integrity.
The technical implementation of this vulnerability stems from inadequate input validation within the kernel's cryptographic subsystem. When processing X.509 certificates, the kernel must generate unique identifiers for asymmetric keys based on certificate content including serial numbers, issuer names, and other ASN.1 encoded fields. These fields can theoretically contain arbitrarily large values that, when combined with the fixed-size structure overhead, exceed the maximum representable value for the integer type used in the calculation. The vulnerability directly relates to CWE-190, which addresses integer overflow conditions, and specifically targets the improper handling of arithmetic operations that can result in buffer overflows. The implementation lacks the check_add_overflow() function that would detect such conditions and prevent the subsequent buffer operations from proceeding with invalid calculated sizes.
The operational impact of this vulnerability extends beyond simple memory corruption, potentially enabling attackers to execute arbitrary code within the kernel context or cause system instability through controlled buffer overflows. When malicious certificates contain oversized ASN.1 INTEGER serial numbers or extended issuer names, the kernel's asymmetric key processing routine could allocate insufficient memory buffers, leading to memory corruption that might be exploitable through carefully crafted attack vectors. This vulnerability affects systems that process X.509 certificates through the Linux kernel's asymmetric key infrastructure, particularly those implementing certificate validation, PKI operations, or secure communication protocols that rely on kernel-level certificate handling. The attack surface includes any system that accepts and processes X.509 certificates for authentication, encryption, or digital signature verification purposes.
Mitigation strategies for CVE-2025-68724 should prioritize immediate kernel updates from trusted vendors that implement the recommended check_add_overflow() protection mechanism. System administrators must ensure all kernel components are updated to versions containing the patched asymmetric_key_generate_id function that properly validates integer arithmetic operations before buffer allocation. The fix aligns with ATT&CK technique T1068 which involves exploiting local privileges to gain kernel-level access, making proper input validation and overflow protection critical defensive measures. Organizations should also implement certificate validation policies that restrict the size and complexity of certificate fields processed by kernel components, though the primary defense remains the patched kernel implementation. Additional monitoring should focus on certificate processing activities and memory allocation patterns that might indicate exploitation attempts, while network segmentation and access controls can limit potential attack vectors that could leverage this vulnerability for privilege escalation or system compromise.