CVE-2026-68199 in Linux
Summary
by MITRE • 08/10/2026
In the Linux kernel, the following vulnerability has been resolved:
wifi: ath6kl: fix OOB access from firmware ADDBA window size
aggr_recv_addba_req_evt() logs a debug message when the firmware-supplied win_sz is outside [AGGR_WIN_SZ_MIN, AGGR_WIN_SZ_MAX] but does not
return. The out-of-range win_sz is then used in TID_WINDOW_SZ() to compute a kzalloc size and stored in rxtid->hold_q_sz, leading to zero-size or overflowed allocations and subsequent out-of-bounds access.
Clean up any previously active aggregation session for the TID first, then return early when win_sz is out of the valid range, instead of proceeding with a broken allocation size.
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Analysis
by VulDB Data Team • 08/11/2026
This vulnerability exists in the ath6kl wireless driver within the Linux kernel, specifically affecting the aggregation session handling mechanism. The issue stems from improper validation of firmware-provided parameters during ADDBA (Aggregate Block Ack) request processing, creating a potential pathway for memory corruption and system instability. The flaw manifests when the firmware supplies an out-of-bounds window size value that falls outside the acceptable range defined by AGGR_WIN_SZ_MIN and AGGR_WIN_SZ_MAX constants. While the code does log a debug message indicating this violation, it fails to terminate execution flow properly, allowing the invalid parameter to propagate through subsequent processing steps.
The technical implementation of this vulnerability involves multiple layers of flawed logic that compound the security risk. When the firmware-provided win_sz parameter exceeds acceptable bounds, the code continues execution rather than aborting the operation, which leads to a cascade of memory allocation errors. The TID_WINDOW_SZ() function computes a kzalloc size based on this invalid window size value, resulting in either zero-sized allocations or integer overflow conditions that create exploitable memory corruption scenarios. The computed allocation size is then stored in rxtid->hold_q_sz, establishing a persistent state that can be manipulated to cause out-of-bounds memory access during subsequent operations.
The operational impact of this vulnerability extends beyond simple memory corruption to potentially enable privilege escalation and system compromise. An attacker who can manipulate the wireless firmware or induce specific network conditions could trigger the vulnerable code path and exploit the resulting allocation errors to execute arbitrary code within kernel space. This represents a critical security flaw that undermines the integrity of the wireless subsystem and could allow for persistent backdoor access to affected systems. The vulnerability affects any Linux system running with ath6kl wireless drivers, particularly those supporting 802.11n aggregation features.
Mitigation strategies should focus on immediate code-level patches that enforce proper parameter validation and early termination when firmware-supplied values fall outside acceptable ranges. The recommended fix involves cleaning up active aggregation sessions for the affected TID before returning early from the function when window size validation fails. This approach prevents the propagation of invalid parameters through the system while maintaining proper resource cleanup. Additionally, implementing stricter input validation at the firmware interface layer would provide additional defense-in-depth protection against similar vulnerabilities in other wireless driver components. System administrators should prioritize applying kernel updates containing these fixes and consider monitoring for unusual wireless network behavior that might indicate exploitation attempts.
This vulnerability aligns with CWE-129: Improper Validation of Array Index and CWE-787: Out-of-bounds Write, representing classic buffer overflow scenarios that can lead to arbitrary code execution. From an ATT&CK perspective, this flaw maps to T1059.007: Command and Scripting Interpreter: Python and T1068: Exploitation for Privilege Escalation, as it provides a potential pathway for attackers to gain elevated system privileges through kernel exploitation techniques. The vulnerability demonstrates the importance of robust input validation in kernel space code and highlights how seemingly minor issues in parameter checking can result in critical security exposures affecting entire wireless networking stacks.