CVE-2015-1421

What it actually does

Use-after-free in sctp_assoc_update allows remote triggering of INIT collisions that corrupt shared-key handling in the SCTP association structure, resulting in slab memory corruption that can lead to kernel panic or arbitrary impact.

Why it matters to the business

Linux systems using SCTP networking can experience sudden crashes or be taken over by remote attackers, causing service outages and potential compromise of network-facing infrastructure.

How an attack unfolds

An attacker sends a sequence of SCTP INIT packets designed to collide on an existing association, forcing improper reuse of freed shared-key data and corrupting kernel memory structures.

How to fix it

Upgrade the Linux kernel to version 3.18.8 or later; apply vendor backports for affected distributions such as Ubuntu and Debian; disable SCTP if not required.

How to confirm the fix worked

Verify running kernel is at least 3.18.8; confirm SCTP module is either updated or blacklisted; test connectivity with benign SCTP traffic to ensure no panic occurs.

Typical attack path

1. Identify target Linux host reachable on SCTP port
2. Craft and send INIT packets that trigger association collision
3. Trigger use-after-free in sctp_assoc_update
4. Leverage resulting slab corruption for denial of service or further exploitation

How to detect it

Search kernel logs for oops, panic, or slab corruption messages referencing sctp_assoc_update; inspect network captures for anomalous SCTP INIT traffic patterns; review system crash dumps for freed association structures.

What your security team should do

• Apply kernel updates immediately on all exposed systems
• Review and restrict SCTP exposure via firewall rules
• Monitor for kernel oops/panic logs related to sctp_assoc_update
• Plan staged rollout of patched kernels across fleets