CVE-2024-27419

What it actually does

Unprotected concurrent access to the sysctl_net_busy_read value in the netrom subsystem allows a data race where a reader may observe an inconsistent value during modification by another thread.

Why it matters to the business

On systems using the netrom protocol, a local user could trigger kernel instability or denial of service under specific timing conditions, though widespread operational impact remains low given the protocol's limited modern use and the flaw's high exploitation complexity.

How an attack unfolds

An attacker with local access races a sysctl write against a concurrent reader in the netrom stack, causing the reader to dereference an inconsistent value and potentially crash the kernel or disrupt network handling; no named threat actors have been observed exploiting this race.

How to fix it

Update the Linux kernel to a version containing commit d623fd5298d95b65d27ef5a618ebf39541074856 or later; rebuild and reboot with the patched kernel image.

How to confirm the fix worked

Confirm the running kernel contains commit d623fd5298d95b65d27ef5a618ebf39541074856 via git log or kernel version string, then attempt concurrent sysctl access under load to verify absence of races.

Typical attack path

1. Obtain local user access on a Linux system running an affected kernel
2. Identify and trigger concurrent modification of the netrom sysctl_net_busy_read tunable
3. Force a reader path to access the value during the write window
4. Trigger kernel panic or network disruption from the resulting inconsistent state

How to detect it

Review kernel logs for netrom-related oops or panic entries around sysctl access; no public exploitation artifacts have been reported.

What your security team should do

• Prioritize patching production kernels that expose netrom interfaces within the next maintenance window
• Monitor upstream stable branches for backports of the referenced commit
• Restrict unprivileged local access on systems where netrom remains enabled