CVE-2026-98566 in Linux
Summary
by MITRE • 10/18/2026
In the Linux kernel, the following vulnerability has been resolved:
drm/imagination: clamp freelist reconstruction requests
The firmware reconstruction count controls accesses to the request's fixed freelist ID array and the copy into the fixed response array. Neither access currently bounds the count to those protocol arrays.
Clamp the count to the request capacity, which is shared by the response layout, and use that count consistently for reconstruction and response publication. Keep the firmware recovery exchange instead of dropping an oversized request without a response, as discussed with the firmware maintainer.
The issue was found by our static-analysis tool.
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Analysis
by VulDB Data Team • 10/18/2026
This vulnerability resides within the Linux kernel's display manager subsystem, specifically affecting the driver for Imagination Technologies graphics hardware. The core technical flaw is a lack of input validation regarding the frequency list reconstruction count provided in firmware requests. This control value dictates how many elements are accessed from a fixed-size freelist ID array and subsequently copied into a fixed response array. Because neither access operation bounds this count to the actual capacity of these protocol arrays, an oversized or maliciously crafted request can cause out-of-bounds memory reads during reconstruction and out-of-bounds writes during the publication of the response. This represents a classic buffer overflow scenario where the software fails to enforce boundary checks on data derived from external sources before performing array operations.
The operational impact of this flaw is significant, as it allows for potential arbitrary code execution or system instability depending on how the kernel handles the memory corruption. If an attacker can trigger this condition through user-space applications interacting with the graphics driver, they may overwrite adjacent kernel structures, leading to privilege escalation. Alternatively, if the out-of-bounds access triggers a page fault in an unsafe context, it could result in a denial of service by crashing the kernel or freezing the display subsystem. The vulnerability was identified using static analysis tools, which are effective at detecting such missing bounds checks before they can be exploited in production environments.
From a classification perspective, this issue aligns with CWE-120 Buffer Copy without Checking Size of Input Classic and CWE-787 Out-of-bounds Write. In the context of the MITRE ATT&CK framework for Linux systems, this vulnerability facilitates techniques related to privilege escalation via kernel exploitation or denial of service through system instability. The lack of validation on input data from firmware interfaces is a common pattern in driver development that requires strict adherence to defensive programming principles.
To mitigate this risk, the fix involves clamping the reconstruction count to match the request capacity, which is shared by the response layout. This ensures that both the reconstruction process and the subsequent publication of responses operate within safe memory boundaries. By maintaining firmware recovery exchanges rather than silently dropping oversized requests without a response, the system preserves protocol integrity while preventing memory corruption. System administrators should ensure their kernels are updated to include this patch, as it addresses a fundamental security gap in how driver-level data structures handle external inputs. Regular application of static analysis tools during development cycles can further prevent similar vulnerabilities by catching missing bounds checks early in the software lifecycle.