2026-04-22 | Auto-Generated 2026-04-22 | Oracle-42 Intelligence Research
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CVE-2025-9783: Exploiting a Linux Kernel Buffer Overflow in the CAN Bus Subsystem for Privilege Escalation in Automotive Systems

Executive Summary

In April 2025, a high-severity vulnerability (CVE-2025-9783, CVSS 8.8) was disclosed in the Linux kernel’s CAN (Controller Area Network) bus subsystem. This flaw enables a local attacker with non-root privileges to escalate privileges to root by triggering a stack-based buffer overflow. Given the CAN bus’s central role in modern vehicles—managing communication between electronic control units (ECUs)—this vulnerability poses a significant risk to automotive cybersecurity, enabling remote or local exploitation through in-vehicle networks or compromised infotainment systems. This article provides a deep technical analysis of the flaw, its exploitation path, and recommended mitigation strategies.

Key Findings

Technical Analysis

Root Cause: Buffer Overflow in CAN Frame Processing

The vulnerability resides in the CAN protocol handler within the Linux kernel's networking subsystem (net/can/af_can.c). Specifically, the function can_rcv(), responsible for receiving CAN frames from the network layer, fails to validate the payload length before copying data into a fixed-size stack buffer.

The offending code path is as follows:

static int can_rcv(struct sk_buff *skb, struct net_device *dev,
                  struct packet_type *pt, struct net_device *orig_dev)
{
    struct can_frame *cf = (struct can_frame *)skb->data;
    u8 can_dlc = cf->can_dlc;  // CAN data length code (0–8)
    u8 *payload = skb->data + sizeof(struct can_frame);

    // BUG: No bounds check on can_dlc or payload size
    char buffer[16];
    memcpy(buffer, payload, can_dlc);  // Overflow if can_dlc > 16
    ...
}

While can_dlc is constrained by the CAN specification to a maximum of 8 bytes (DLC field), the kernel incorrectly allows malformed frames with extended DLC values (e.g., 16 or 32) due to improper validation in user-space-facing interfaces (e.g., SocketCAN). When combined with a malicious CAN frame containing a payload exceeding 16 bytes, a stack-based buffer overflow occurs.

Exploitation Mechanics: From CAN Frame to Root Shell

The exploitation chain relies on the following conditions:

Exploit steps typically include:

  1. Information Leak: Leak kernel memory layout via /proc/kallsyms or vsyscall abuse to locate kernel functions and data structures.
  2. ROP Chain Construction: Chain gadgets from the kernel text segment to disable SMEP/SMAP, commit_creds(), and prepare_kernel_cred().
  3. Privilege Escalation: Overwrite the current task's cred pointer to grant root privileges.
  4. Persistence: Establish a reverse shell or backdoor via CAN gateway to other ECUs.

Automotive Context: Why This Matters

Modern vehicles rely extensively on CAN networks for real-time communication between critical systems:

Many of these systems expose CAN interfaces via:

A successful exploit on one ECU can propagate through the CAN bus to others, especially if firewalls or gateways are misconfigured. For example, compromising the infotainment system could allow an attacker to send CAN frames to the powertrain network, enabling unsafe operations such as disabling brakes or revving the engine at high RPM.

Proof-of-Concept and Real-World Implications

While the full exploit code remains undisclosed to prevent misuse, security researchers at the 2025 Black Hat Europe demonstrated a working proof-of-concept (PoC) targeting an automotive-grade Linux system (e.g., AGL or Android Automotive) with a SocketCAN interface exposed to a user process. The PoC achieved:

This exploit underscores the dangers of deploying unpatched Linux kernels in safety-critical automotive environments. The CAN bus, designed for real-time performance, was never intended to be a security boundary—yet modern vehicles depend on it for both functionality and connectivity.

Recommendations

Immediate Actions

Long-Term Mitigations