CVE-2024-35823

What it actually does

Use of memcpy on overlapping source and destination buffers in the virtual terminal unicode handling code leads to buffer corruption when deleting characters.

Why it matters to the business

Systems may experience terminal subsystem instability or denial of service under specific input sequences; widespread kernel exposure increases operational risk for servers, containers, and embedded devices until patched.

How an attack unfolds

An attacker supplies crafted input that triggers repeated character deletion operations in the vt unicode buffer, causing memcpy to corrupt adjacent memory due to overlapping regions and resulting in unpredictable kernel behavior.

How to fix it

Update the Linux kernel to a version containing commit fc7dfe3d123f00e720be80b920da287810a1f37d or later; rebuild and deploy the fixed kernel across all affected systems.

How to confirm the fix worked

Verify the presence of the memmove replacement in the vt deletion code path and confirm the kernel build includes the referenced commit; test deletion operations under load to ensure no buffer corruption occurs.

Typical attack path

1. Identify a reachable vt console or pseudoterminal interface
2. Craft input sequences that perform overlapping character deletions
3. Trigger the vulnerable memcpy path repeatedly
4. Observe resulting memory corruption effects such as crashes or undefined behavior

How to detect it

Review kernel logs for vt-related oops or panic messages occurring during character input or deletion; examine any available core dumps or memory analysis artifacts for signs of unicode buffer overwrites.

What your security team should do

• Prioritize kernel updates on internet-facing and multi-tenant systems within standard change windows
• Monitor upstream stable kernel releases for backports of the fix
• Review terminal and console usage in high-availability workloads for additional hardening opportunities