CVE-2023-53000

CVE-2023-53000 is a vulnerability in the Linux kernel's netlink subsystem that enables potential Spectre v1 gadgets. During netlink attribute parsing in functions like __nla_validate_parse() or validate_nla(), the attribute type is extracted as a u16 and validated against maxtype, but its subsequent use as an array index lacks protection against speculative execution. This allows the type value to serve as a Spectre v1 gadget, potentially leaking kernel memory contents to malicious users. The issue is classified under CWE-129 (Improper Validation of Array Index) with a CVSS 3.1 score of 7.8 (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H).

A local attacker with low privileges can exploit this vulnerability by crafting malicious netlink messages that trigger the unprotected array indexing during parsing. Successful exploitation relies on Spectre v1 speculative execution to access out-of-bounds kernel memory, enabling information disclosure. The high CVSS impacts reflect potential for significant confidentiality loss, along with integrity and availability disruptions from the resulting kernel state corruption or denial of service.

Mitigation requires updating to patched Linux kernel versions incorporating the referenced stable commits, such as 3e5082b1c66c7783fbcd79b5b178573230e528ff, 41b74e95f297ac360ca7ed6bf200100717cb6c45, 539ca5dcbc91134bbe2c45677811c31d8b030d2d, 992e4ff7116a77968039277b5d6aaa535c2f2184, and f0950402e8c76e7dcb08563f1b4e8000fbc62455. These patches insert array_index_nospec() barriers to prevent the gadgets in most netlink parsing paths, though the fix recommends a broader audit for non-centralized validation cases.