CVE-2024-53043

What it actually does

Missing NULL checks on daddr and saddr in the MCTP I2C transmit path allow a packet to be processed without a valid neighbour table entry or source address, leading to invalid memory access or kernel instability.

Why it matters to the business

Systems running the affected older Ubuntu kernels that use MCTP over I2C can experience crashes or degraded networking, increasing downtime and operational risk; the large number of affected LTS releases amplifies exposure across legacy deployments.

How an attack unfolds

An attacker triggers transmission of an MCTP packet over I2C when no neighbour entry exists (causing daddr to be NULL) or via an alternate protocol path (causing saddr to be NULL), resulting in the kernel attempting to use the NULL address and crashing or behaving unexpectedly. Generic Linux kernel exploitation campaigns observed in 2024 could leverage similar resource-handling flaws.

How to fix it

Upgrade to the listed fixed package versions for each affected release: linux 3.13.0-79.123 (14.04), linux-aws 4.4.0-1002.2 (14.04), linux-lts-xenial 4.4.0-13.29~14.04.1, linux 4.4.0-2.16 (16.04), linux-aws 4.4.0-1001.10 (16.04), linux-gke 4.4.0-1003.3, linux-hwe 4.8.0-36.36~16.04.1, linux-raspi2 4.4.0-1003.4, linux-snapdragon 4.4.0-1012.12, and equivalent fixed versions for lts-utopic, lts-vivid, and lts-wily.

How to confirm the fix worked

Verify the running kernel package version matches or exceeds the fixed versions above; confirm absence of the vulnerable mctp_i2c code path by inspecting source or testing that NULL daddr/saddr packets are dropped cleanly without oops.

Typical attack path

1. Identify a target system running an unpatched affected Ubuntu linux package with MCTP I2C enabled
2. Cause or observe absence of a neighbour table entry for the destination
3. Transmit an MCTP packet that reaches the I2C driver without a valid daddr or saddr
4. Trigger NULL dereference or invalid access leading to denial of service

How to detect it

Review kernel logs (dmesg, /var/log/kern.log, journalctl) for oops or panic messages referencing mctp_i2c or NULL pointer dereference around MCTP transmit; correlate with network activity involving I2C or MCTP sockets.

What your security team should do

• Apply the exact fixed package versions immediately on all affected Ubuntu 14.04/16.04 systems
• Disable MCTP I2C interfaces where not required until patches are deployed
• Monitor for kernel oops or crashes involving mctp_i2c after applying updates