CVE-2026-74408 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
wifi: ath9k: fix OOB access from firmware tx status queue ID
ath_tx_edma_tasklet() accesses sc->tx.txq[ts.qid] where ts.qid is a
4-bit hardware field (0-15), but the txq array only has ATH9K_NUM_TX_QUEUES (10) entries. A qid >= 10 causes an OOB array access.
Add a bounds check on ts.qid before using it as an array index.
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Analysis
by VulDB Data Team • 08/15/2026
The vulnerability identified in the Linux kernel's ath9k wireless driver represents a critical out-of-bounds memory access flaw that could potentially lead to system instability or privilege escalation. This issue resides within the ath_tx_edma_tasklet() function which processes transmission status updates from wireless firmware, specifically when handling the tx_status queue ID field. The flaw demonstrates a classic buffer overflow pattern where hardware-provided indexing values are used without proper validation against the actual array dimensions.
The technical implementation of this vulnerability stems from a fundamental mismatch between hardware field size and software array allocation. The ts.qid field is defined as a 4-bit hardware field capable of representing values from 0 to 15, while the sc->tx.txq array contains only ATH9K_NUM_TX_QUEUES entries totaling 10 elements. This discrepancy creates an exploitable condition where firmware-generated queue IDs exceeding the allocated array bounds can result in memory corruption. The vulnerability operates at the kernel level within wireless networking subsystem and directly impacts the ath9k driver's ability to properly manage transmission queues.
From an operational perspective, this out-of-bounds access represents a significant security risk that could manifest through multiple attack vectors. The flaw aligns with CWE-129: "Improper Validation of Array Index" and demonstrates characteristics consistent with ATT&CK technique T1068: "Exploitation for Privilege Escalation." An attacker who can influence the firmware to generate queue IDs greater than 9 could potentially cause memory corruption that might lead to kernel panic, denial of service, or more severe exploitation depending on the specific memory layout and access patterns. The impact extends beyond simple functionality degradation to potential system compromise.
The remediation for this vulnerability requires implementing a straightforward bounds check mechanism that validates ts.qid against the valid array dimensions before utilizing it as an index. This approach directly addresses the root cause by ensuring that hardware-provided indexing values are properly constrained within acceptable ranges. The fix demonstrates adherence to secure coding practices and follows the principle of input validation as outlined in industry standards. Implementation should be straightforward since it involves adding a simple conditional check that prevents array access when qid exceeds ATH9K_NUM_TX_QUEUES minus one, thereby preventing the out-of-bounds memory access while maintaining all legitimate functionality of the wireless driver subsystem.