CVE-2026-63824 in Linux
Summary
by MITRE • 07/19/2026
In the Linux kernel, the following vulnerability has been resolved:
KEYS: fix overflow in keyctl_pkey_params_get_2()
The length for the internal output buffer is calculated incorrectly, which can result overflow when a too small buffer is provided.
Fix the bug by allocating internal output with the size of the maximum length of the cryptographic primitive instead of caller provided size.
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Analysis
by VulDB Data Team • 07/19/2026
This vulnerability resides in the linux kernel's key management subsystem specifically within the keyctl_pkey_params_get_2() function which handles public key parameter retrieval operations. The flaw represents a classic buffer overflow condition that occurs when the kernel incorrectly calculates the size of an internal output buffer used for cryptographic primitive parameters. This improper buffer sizing calculation creates a scenario where malicious actors could potentially trigger memory corruption through carefully crafted input parameters.
The technical implementation issue stems from the function's approach to buffer allocation where it uses the caller-provided buffer size rather than the maximum required size for the cryptographic operations it performs. This approach violates fundamental security principles of defensive programming and can lead to arbitrary code execution or system instability when the internal buffer overflows past its allocated boundaries. The vulnerability specifically affects the kernel's handling of public key infrastructure operations and demonstrates a clear failure in input validation and resource management.
From an operational perspective this vulnerability poses significant risks to systems relying on kernel-level key management services, particularly those implementing cryptographic protocols that depend on proper parameter handling. Attackers could exploit this condition to execute arbitrary code with kernel privileges, potentially leading to complete system compromise. The impact extends beyond simple memory corruption as it affects the integrity of the entire kernel's key management framework and could enable privilege escalation attacks that align with tactics described in the attack pattern taxonomy under technique T1068 for bypassing system protections.
The fix implemented addresses the core issue by changing the buffer allocation strategy to use the maximum length required for cryptographic primitives rather than the potentially smaller caller-provided size. This approach follows established security practices for preventing buffer overflows and aligns with common weakness enumerations categorized under CWE-121 for heap-based buffer overflow conditions. The mitigation strategy ensures that regardless of input parameters provided by userspace applications, the kernel maintains sufficient internal resources to handle cryptographic operations safely without risking memory corruption.
This vulnerability highlights the importance of proper resource management in kernel space operations and demonstrates why cryptographic functions require careful attention to buffer sizing and validation. The fix represents a defensive programming approach that prevents attackers from manipulating buffer sizes to trigger overflow conditions, thereby maintaining system stability and security. Organizations should prioritize applying this patch immediately as it addresses a critical exposure point within the kernel's core security infrastructure, particularly affecting systems running older kernel versions where such cryptographic operations are actively utilized by various security services and applications.