CVE-2023-1249

What it actually does

A use-after-free vulnerability in the Linux kernel's core dump subsystem allows a local user to trigger a kernel panic and crash the system when the vma snapshot patch in fill_files_note is absent.

Why it matters to the business

Local users on unpatched Linux systems can cause denial-of-service crashes, resulting in unplanned downtime, potential loss of in-memory data, and disruption to services running on affected kernels.

How an attack unfolds

An attacker with local shell access on a vulnerable Linux kernel induces a core dump, exploiting the use-after-free condition in the coredump path to force a kernel panic and system crash.

How to fix it

Upgrade the Linux kernel to a version containing commit 4b0986a3613c92f4ec1bdc7f60ec66fea135991f which snapshots the vma during fill_files_note processing.

How to confirm the fix worked

Confirm the running kernel source tree contains commit 4b0986a3613c92f4ec1bdc7f60ec66fea135991f and verify that core-dump scenarios no longer produce use-after-free warnings or panics.

Typical attack path

1. Gain local user access on the target Linux system
2. Cause a process to terminate in a manner that triggers core dump handling
3. Trigger the unpatched use-after-free in the core dump subsystem to induce kernel panic

How to detect it

Review kernel logs and crash dumps for panic messages originating from the coredump or fill_files_note code paths on Linux hosts.

What your security team should do

• Apply the kernel commit 4b0986a3613c92f4ec1bdc7f60ec66fea135991f or later fixed release on all affected Linux systems
• Limit local user accounts and privileges to reduce exposure surface
• Monitor kernel logs for coredump-related panics until patches are deployed