Linux Kernel TLS Protocol Vulnerability Allows Local Information Disclosure
A local information disclosure vulnerability in the Linux Kernel's TLS protocol requires high-privileged code execution to exploit.
A local information disclosure vulnerability has been identified within the Transport Layer Security (TLS) protocol implementation in the Linux Kernel. Tracked as CVE-2026-64046, this flaw allows attackers who have already gained high-privileged code execution on a target system to access sensitive information.
The vulnerability stems from an issue within the message splicing feature of the TLS protocol. Specifically, the kernel fails to properly validate user-supplied data, leading to an out-of-bounds read. This means the system attempts to read data from a memory location beyond the boundaries of an allocated buffer, potentially exposing confidential data.
Exploitation of this vulnerability is not straightforward. An attacker must first achieve a significant level of access, specifically the ability to execute high-privileged code on the affected system. This prerequisite significantly limits the attack surface, as it implies the system is already compromised to a considerable degree. However, successful exploitation could be leveraged in conjunction with other vulnerabilities to achieve arbitrary code execution within the kernel's context.
The Zero Day Initiative (ZDI), which disclosed the vulnerability, assigned it a CVSS score of 6.7, classifying it as medium-high severity. This score reflects the potential impact of the vulnerability, balanced against the prerequisite of prior high-privileged access.
Linux has released a patch to address this vulnerability. The fix is detailed in a commit to the Linux kernel repository, indicating that developers have implemented proper validation for user-supplied data within the message splicing mechanism to prevent out-of-bounds reads.
This vulnerability was reported to the vendor on June 10, 2026, and the coordinated public release of the advisory occurred on September 14, 2026. The advisory was updated on the same day. The discovery and reporting are credited to researchers Manas Ghandat and Rakshit Awasthi.
While the vulnerability requires a high degree of prior compromise, its presence in the core Linux kernel highlights the ongoing challenges in securing complex software components. Information disclosure vulnerabilities, even when requiring significant initial access, can be valuable tools for attackers seeking to escalate privileges or gather intelligence for further attacks.
Users and administrators are strongly advised to apply the available patches for the Linux kernel to mitigate this risk. Keeping systems updated is a fundamental security practice that helps protect against a wide range of known vulnerabilities.