CVE-2026-93065 in Linux
Summary
by MITRE • 09/17/2026
In the Linux kernel, the following vulnerability has been resolved:
wifi: iwlwifi: fix counter type in iwl_fwrt_dump_error_logs
The loop counter 'count' was declared as u8 while num_pc is u32. If firmware advertises more than 255 PC entries the counter wraps back to zero and the loop never terminates potentially causing an infinite loop or reading past the allocated pc_data array.
Change the declaration to u32 to match num_pc.
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Analysis
by VulDB Data Team • 09/17/2026
The vulnerability identified in the Linux kernel's iwlwifi driver, specifically within the function iwl_fwrt_dump_error_logs, represents a classic integer truncation issue that can lead to severe operational instability and potential security compromises. The root cause lies in a type mismatch between the loop counter variable count, which is declared as an unsigned 8-bit integer (u8), and the source value num_pc, which is defined as an unsigned 32-bit integer (u32). This discrepancy becomes critical when firmware devices advertise more than two hundred fifty-five Program Counter entries. In such scenarios, the assignment of a larger u32 value to the smaller u8 counter results in truncation, where only the least significant eight bits are retained. Consequently, if the actual number of PC entries exceeds 255, the truncated count will wrap around to zero or another small integer rather than reflecting the true magnitude of data required for processing.
This type mismatch directly facilitates an infinite loop condition within the logging mechanism. As the counter wraps back to a value that does not accurately reflect the remaining iterations needed to process all PC entries, the loop termination condition fails to trigger appropriately. The code continues to iterate beyond the bounds of the allocated pc_data array, leading to out-of-bounds memory access. This behavior constitutes an off-by-one or buffer over-read vulnerability depending on the specific implementation details and boundary conditions. An attacker who can influence the firmware's advertised capabilities or manipulate the state that triggers this logging routine could potentially exploit this flaw to cause a denial of service by hanging the kernel thread responsible for handling Wi-Fi errors, thereby disrupting network connectivity and system stability.
From a security taxonomy perspective, this vulnerability aligns with CWE-197, which describes numeric truncation errors where larger data types are improperly assigned to smaller ones without adequate validation or casting safeguards. Furthermore, the resulting behavior of reading past allocated memory boundaries falls under CWE-125, specifically Out-of-bounds Read, as the loop accesses pc_data entries that do not exist within the reserved buffer space. In terms of adversarial tactics, this flaw could be leveraged to achieve Denial of Service against network services, mapping to MITRE ATT&CK technique T1499, Endpoint Denial of Service, particularly through resource exhaustion via infinite loops or kernel panics resulting from memory corruption. The lack of bounds checking before the loop execution allows for predictable exploitation paths that do not require complex bypass techniques, relying instead on specific firmware configurations or states to trigger the overflow condition.
Mitigation strategies must focus on correcting the data type declaration and implementing robust validation checks. The primary fix involves changing the variable count from u8 to u32 to ensure it can accurately hold values up to four billion two hundred ninety-five million, thereby eliminating the truncation issue entirely. Additionally, defensive programming practices should be adopted by adding explicit bounds checking before entering loops that depend on external or firmware-supplied data lengths. Developers should validate that num_pc does not exceed a predefined maximum threshold consistent with the allocated array size prior to initiating any iteration logic. This ensures that even if future firmware versions advertise unexpected values, the system will fail safely rather than executing undefined behavior. Updating the iwlwifi driver to include this patch is essential for maintaining kernel integrity and preventing potential denial of service attacks targeting wireless subsystems in Linux-based environments.