CVE-2023-28772

What it actually does

Buffer overflow in seq_buf_putmem_hex within lib/seq_buf.c allows out-of-bounds writes when formatting hexadecimal memory dumps.

Why it matters to the business

Local attackers with elevated privileges can corrupt kernel memory, leading to crashes, denial of service, or potential privilege escalation on affected Linux systems; widespread kernel usage increases exposure across servers and devices.

How an attack unfolds

An attacker with root-level access crafts input that triggers excessive data writes through seq_buf_putmem_hex, overflowing the buffer and corrupting adjacent kernel structures to achieve code execution or system instability.

How to fix it

Upgrade the Linux kernel to a version containing commit eaf05d42c0d2f7be204ac2eea859524078d85763 or later (kernel 5.13.3 and newer); rebuild and reboot with the patched kernel.

How to confirm the fix worked

Verify running kernel version is 5.13.3 or newer; inspect source for presence of the fixing commit in lib/seq_buf.c; test affected seq_buf functions under load for proper bounds handling.

Typical attack path

1. Obtain high-privilege local access on target system
2. Identify or trigger code paths invoking seq_buf_putmem_hex with oversized input
3. Perform out-of-bounds write to corrupt kernel memory
4. Leverage corruption for privilege escalation or denial of service

How to detect it

Review kernel logs for buffer-related warnings or panics around seq_buf operations; correlate with process activity that invokes hexadecimal dumping routines; examine audit logs for unusual privileged local access patterns.

What your security team should do

• Apply kernel updates containing the fix immediately on all affected systems
• Restrict local high-privilege accounts to minimize attack surface
• Monitor for kernel panics or unexpected seq_buf activity in system logs
• Prioritize patching in environments with high downstream kernel dependents