Impact
The QAT driver in the Linux kernel exposed a legacy character device (qat_adf_ctl) with several undocumented IOCTLs that were not part of the public API and had no known users. These unused interfaces expanded the kernel’s attack surface and introduced code paths that were only reachable via those IOCTLs. The vulnerability is mitigated by removing the character device, the IOCTL definitions, and associated structures, thereby eliminating the exposed functionality and associated dead code.
Affected Systems
The issue applies to any Linux kernel build that includes the QAT driver before the patches removing the legacy device and IOCTLs. Systems running kernels that load the qat module and expose the /dev/qat_adf_ctl device are affected until the code changes are applied.
Risk and Exploitability
The EPSS score is below 1% and the vulnerability is not listed in CISA KEV, indicating a low empirical exploitation probability at present. The CVSS score of 7.8 classifies the vulnerability as high severity. The IOCTL interface has no documented legitimate users and is not exposed via public APIs, so typical unprivileged usage is unlikely to trigger it. However, a process with root or sufficient kernel privileges could invoke these legacy IOCTLs if the obsolete device remains on a system not yet updated.
OpenCVE Enrichment
Debian DLA
Ubuntu USN