CVE-2024-56539

What it actually does

The flaw is a struct definition using a one-element array for SSID storage in mwifiex_ie_types_wildcard_ssid_params, causing a field-spanning memcpy write warning (and potential improper memory access) when copying variable-length SSIDs during network scans in the mwifiex wireless driver.

Why it matters to the business

Wireless network scanning on affected Linux systems (including certain Chromebooks) can trigger kernel warnings or instability, potentially disrupting connectivity and requiring driver updates; high ecosystem prevalence in Linux kernel deployments increases urgency for patching.

How an attack unfolds

An attacker with local access or ability to influence wireless scan parameters sends crafted SSID data that triggers the memcpy operation exceeding the declared one-element field size, leading to out-of-bounds writes; threat actors in 2024 zero-day campaigns and Linux kernel out-of-bounds write activities have targeted similar kernel issues.

How to fix it

Update the Linux kernel to commit a09760c513ae0f98c7082a1deace7fb6284ee866 or later; for listed Ubuntu packages apply the exact fixed versions such as libksba 1.3.0-3ubuntu0.14.04.2 or 1.3.3-1ubuntu0.16.04.1; rebuild and deploy kernel images with the flexible-array member change.

How to confirm the fix worked

Confirm the struct uses a flexible array member for ssid instead of a one-element array; recompile with warnings enabled and verify absence of the field-spanning memcpy warning at scan.c:904; test wireless scans on affected hardware like MT8173.

Typical attack path

1. Identify systems running vulnerable mwifiex driver in Linux kernel
2. Trigger or coerce a wireless scan operation with specific SSID lengths
3. Cause memcpy to perform field-spanning write on wildcard_ssid_tlv->ssid
4. Exploit resulting memory corruption for privilege escalation or denial of service

How to detect it

Review kernel logs for the exact memcpy warning string mentioning wildcard_ssid_tlv->ssid and scan.c:904; inspect dmesg or syslog for mwifiex_scan_networks stack traces on systems with Marvell wireless hardware; correlate with threat actor activity on Linux kernel out-of-bounds writes.

• memcpy: detected field-spanning write (size 6) of single field "wildcard_ssid_tlv->ssid"
• mwifiex_scan_networks+0x4fc/0xf28 [mwifiex]
• WARNING: CPU.*PID.*at drivers/net/wireless/marvell/mwifiex/scan.c:904

What your security team should do

• Prioritize kernel updates on all systems using mwifiex wireless drivers due to 654 days since publication and active Linux kernel exploit campaigns
• Monitor EPSS trend and apply fixes within CISA timelines if KEV status changes
• Audit downstream dependents for kernel version exposure and test scan functionality post-update