CVE-2026-93079
HighCVSS 7.8Exploitation Probability (EPSS)
Low risk6th percentile - higher than 6% of all known CVEs
Summary
In the Linux kernel, the cxl/features module's cxlctl_get_feature() sizes its output buffer from the user's fwctl_rpc.out_len but tells the device to write cxl_mbox_get_feat_in.count bytes, where count is a separate user-controlled value. Nothing bounds count against out_len, so a small out_len with a large count overflows the kvzalloc()'d buffer, causing a heap out-of-bounds write reachable from FWCTL_RPC.
Risk Assessment
A heap out-of-bounds write reachable via FWCTL_RPC can lead to privilege escalation or kernel crash. It requires local access to the FWCTL interface.
Recommendation
Update the Linux kernel to a version with the fix. Restrict access to the FWCTL_RPC interface to trusted users.
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Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: cxl/features: Reject Get Feature count larger than the output buffer cxlctl_get_feature() sizes its output buffer from the user's fwctl_rpc.out_len, but the device is told to write cxl_mbox_get_feat_in.count bytes into rpc_out->payload, which is a separate user-controlled value. Nothing bounds count against out_len, so a small out_len with a large count overflows the kvzalloc()'d buffer. A heap OOB write reachable from FWCTL_RPC. Reject requests where count exceeds the available payload room, before allocating.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS