CVE-2023-2177

What it actually does

Null pointer dereference in SCTP stream scheduling code (net/sctp/stream_sched.c) where a failed stream_in allocation leads to use-after-free access on stream_out, triggering a kernel panic.

Why it matters to the business

Local authenticated users on affected Linux systems can trigger a denial of service by crashing the kernel; no remote or unauthenticated exploitation path exists and the issue has not appeared in ransomware campaigns.

How an attack unfolds

An attacker with local shell access crafts SCTP socket operations that force allocation failure for an incoming stream; the kernel then frees the outgoing stream structure and subsequently dereferences it, causing an immediate system crash.

How to fix it

Upgrade the Linux kernel to a version containing commit 3d7cb6b04c3f3115719235cc6866b10326de34cd or later; apply the vendor-supplied package update for the affected distribution.

How to confirm the fix worked

Verify the running kernel contains commit 3d7cb6b04c3f3115719235cc6866b10326de34cd; confirm the vulnerable code path in stream_sched.c is no longer present by inspecting the source or checking the kernel build log.

Typical attack path

1. Obtain local user access on a vulnerable Linux host
2. Create or manipulate SCTP sockets to trigger stream_in allocation failure
3. Force the kernel to free stream_out and then access the freed pointer
4. Trigger kernel panic resulting in denial of service

How to detect it

Review kernel logs for oops or panic messages containing references to sctp/stream_sched.c or stream allocation failures; correlate with SCTP socket creation events from local processes.

What your security team should do

• Prioritize kernel updates on all systems exposing SCTP sockets
• Limit local user accounts that can create SCTP sockets where feasible
• Monitor for kernel oops/panic events referencing sctp/stream_sched.c