CVE-2026-68439 in Linux
Summary
by MITRE • 08/12/2026
In the Linux kernel, the following vulnerability has been resolved:
wifi: mt76: mt7925: fix possible NULL-pointer deref in mt7925_mcu_bss_he_tlv()
mt76_connac_get_he_phy_cap routine can theoretically return NULL so check cap pointer before dereferencing it.
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Analysis
by VulDB Data Team • 08/12/2026
The vulnerability exists within the mt7925 wireless driver component of the Linux kernel's mt76 subsystem which manages MediaTek wireless network adapters. This specific flaw manifests in the mt7925_mcu_bss_he_tlv() function where a potential null pointer dereference could occur during wireless communication setup processes. The issue stems from the mt76_connac_get_he_phy_cap routine which is responsible for retrieving high efficiency physical layer capabilities but can theoretically return a NULL pointer under certain conditions. When this routine returns NULL, subsequent code attempts to dereference the pointer without proper validation, creating an exploitable condition that could lead to system instability or potential privilege escalation.
The technical nature of this vulnerability aligns with CWE-476 which describes null pointer dereference conditions in software systems. The flaw represents a classic defensive programming error where input validation is insufficient before pointer operations. During normal wireless network operation, when the driver attempts to configure high efficiency wireless capabilities for 802.11ax networks, the system calls into the mt76_connac_get_he_phy_cap function which may legitimately return NULL in edge cases such as hardware initialization failures or malformed firmware responses. The absence of null checks before dereferencing this pointer creates an execution path where a kernel panic or system crash can occur when attempting to access memory through a null reference.
Operationally, this vulnerability impacts systems running Linux kernels with MediaTek mt7925 wireless drivers, particularly those supporting 802.11ax Wi-Fi standards. The vulnerability is most likely to manifest during network connection establishment processes or when switching between different wireless modes that require HE PHY capability negotiation. Attackers could potentially exploit this by triggering specific wireless communication scenarios that cause the driver to call into the vulnerable code path, leading to system crashes or denial of service conditions. While direct privilege escalation is not typically possible through this vector alone, the kernel panic conditions could be leveraged in combination with other exploits or used for persistent denial of service attacks against wireless infrastructure.
The recommended mitigation strategy involves implementing proper null pointer validation before dereferencing the capability pointer returned by mt76_connac_get_he_phy_cap routine. This fix follows standard defensive programming practices and aligns with ATT&CK technique T1068 which covers privilege escalation through kernel exploits, though this particular vulnerability primarily represents a denial of service rather than direct privilege escalation. System administrators should apply the kernel patch that introduces this validation check to prevent exploitation. Additionally, monitoring for kernel panic events related to wireless driver operations can help detect potential exploitation attempts in production environments. The fix demonstrates proper adherence to secure coding practices and represents a fundamental defensive measure against null pointer dereference vulnerabilities that are common across kernel subsystems.