CVE-2025-68738: 
Linux Debian vulnerability analysis and mitigation

CVE-2025-68738 is a null pointer dereference vulnerability in the Linux kernel's mt76 Wi-Fi driver, specifically within the mt7996_conf_tx() function of the mt7996 module. The flaw occurs when a wireless link does not yet have an assigned channel, causing mt7996_vif_link to return NULL, which is subsequently dereferenced. It was published on December 24, 2025, and affects Linux kernel versions introduced from commit c0df2f0caa8dde0d50f36649ee28a54c5079281b up to the patched commits in stable branches. Feedly estimates this as a Medium severity issue, with an EPSS score of approximately 0.017% (Feedly, EUVD).

The root cause is a null pointer dereference (CWE-476) in the mt7996_conf_tx() function within the Linux kernel's drivers/net/wireless/mediatek/mt76/mt7996/ subsystem. When a virtual interface link has not yet been assigned a channel, the helper function mt7996_vif_link() returns NULL; the code previously attempted to use this NULL pointer to store queue configuration parameters, triggering a kernel NULL pointer dereference. The fix relocates the queue parameters (queue params) into the struct mt7996_vif_link structure itself, ensuring settings can be stored and applied later even when no channel is yet assigned (Feedly, EUVD). Patches were applied to multiple stable kernel branches via commits 96841352aaba, b8f34c1c5c4f, and 79277f8ad15e (Kernel Git).

Successful triggering of this vulnerability causes a kernel null pointer dereference, which typically results in a kernel panic (system crash), leading to a denial of service on the affected host. The impact is limited to availability — confidentiality and integrity are not directly affected. Systems using MediaTek MT7996-based Wi-Fi hardware running vulnerable Linux kernel versions are at risk, particularly in scenarios where wireless links are configured before a channel is assigned (Feedly, EUVD).

There is no known public exploit code or evidence of in-the-wild exploitation for CVE-2025-68738. The EPSS score is approximately 0.017%, indicating a very low probability of exploitation in the near term. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. Exploitation would require local access or the ability to trigger specific Wi-Fi configuration operations on a system with an MT7996-based wireless adapter (Feedly).

The Linux kernel maintainers have released patches addressing this vulnerability in multiple stable branches: the fix is included in kernel versions 6.17.13, 6.18.2, and 6.19-rc1, corresponding to commits 96841352aaba7723c20afb3a5356746810ef8198, b8f34c1c5c4f5130c20e3253c95ba1d844d402b9, and 79277f8ad15ec5f255ed0e1427c7a8a3e94e7f52 (Kernel Git, EUVD). Users running affected kernel versions with MT7996-based Wi-Fi hardware should update to a patched kernel release. As a temporary workaround, disabling or not using MT7996-based wireless interfaces may reduce exposure until a patch can be applied.