CVE-2026-98185

What it actually does

Missing bounds check before subtracting fixed header size and BSS length from scan response size allows integer underflow of the TLV buffer length, causing the subsequent TLV parser to read past the end of the allocated command response buffer.

Why it matters to the business

Wireless scan operations on affected Linux systems may trigger kernel memory corruption, leading to driver crashes, loss of Wi-Fi connectivity, or potential information disclosure from kernel memory.

How an attack unfolds

An attacker with the ability to influence or spoof 802.11 scan responses returned by the Marvell Wi-Fi firmware supplies a short response buffer or an oversized BSS descriptor; the driver performs unchecked subtraction, underflows the TLV size calculation, and the parser dereferences memory beyond the response, enabling read or write primitives that can be chained for local privilege escalation.

How to fix it

Update the Linux kernel to a version containing the validation of fixed response fields and BSS length before TLV extent calculation; apply the commit that adds explicit extent checks in mwifiex_ret_802_11_scan for both normal and background scan paths.

How to confirm the fix worked

Confirm the presence of the bounds checks on resp->size against fixed header plus BSS length before any subtraction; verify that tlv_buf_size derivation occurs only after successful validation; test with deliberately malformed scan responses in a controlled environment.

Typical attack path

1. Obtain local access or control over the wireless firmware to craft malicious scan responses
2. Trigger a scan request via the mwifiex driver
3. Supply undersized response or oversized BSS length field
4. Trigger underflow in tlv_buf_size calculation inside mwifiex_ret_802_11_scan
5. Cause out-of-bounds memory access during TLV walk
6. Leverage resulting corruption for further exploitation or denial of service

How to detect it

Review kernel logs for mwifiex scan-related oops, page faults, or warnings around mwifiex_ret_802_11_scan; inspect wireless interface reset or scan failure events that coincide with unusual firmware response sizes; correlate with any process that initiates frequent scans.

What your security team should do

• Prioritize kernel updates on all systems using mwifiex wireless drivers
• Monitor vendor and distribution advisories for backported fixes
• Restrict wireless scanning privileges where possible until patched
• Enable kernel hardening features such as KASAN or hardened usercopy during testing