CVE-2026-8988

Executive Summary

Business Impact: This vulnerability affects the Autel Maxi Charger Single, a device used in the electric vehicle (EV) charging infrastructure. An attacker with physical access could compromise the device's operating system, potentially leading to manipulation of charging operations, theft of sensitive data (e.g., user credentials, payment information), or use of the device as a pivot point into the broader EV charging network. The likely attacker is a malicious insider, a competitor, or a vandal with physical access to the charging station.

Vulnerability Class and Attack Vector: This is a hardware-level vulnerability involving an exposed UART (Universal Asynchronous Receiver-Transmitter) interface. The attack vector is physical; the attacker must have physical access to the device to connect to the UART pins. No network-based exploitation is possible for the initial compromise.

Urgency Assessment: The CVSS score is 0.0 (Informational) and the EPSS probability is 0.0%. This indicates that the vulnerability is not currently being exploited in the wild and is considered low risk from a remote exploitation perspective. However, the physical nature of the attack and the potential for high impact (complete compromise of the device) means that organizations with exposed or unattended charging stations should prioritize physical security controls.

Key Facts:

• Vendor: Autel
• Affected Software: Autel Maxi Charger Single firmware through V1.03.51
• Patch Status: None available as of 2026-07-22.
• CISA KEV: Not listed.

CVSS Breakdown & Threat Level

CVSS Vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Metric Decomposition:

• AV (Attack Vector): Physical (P) - The attacker must have physical access to the device to connect to the UART interface.
• AC (Attack Complexity): Low (L) - No special conditions or complex steps are required. The attacker simply needs to connect a serial terminal to the exposed UART pins.
• PR (Privileges Required): None (N) - No authentication or privileges are needed to access the UART interface.
• UI (User Interaction): None (N) - No user action is required for exploitation.
• S (Scope): Unchanged (U) - The vulnerability affects only the vulnerable component (the Autel charger).
• C (Confidentiality): High (H) - An attacker can read the entire file system, including configuration files, credentials, and user data.
• I (Integrity): High (H) - An attacker can modify the boot configuration, file system, and installed software.
• A (Availability): High (H) - An attacker can disrupt the boot process, corrupt the file system, or render the device inoperable.

Qualitative Severity Label: Informational (CVSS 0.0). The score is 0.0 because the CVSS v3.1 calculator does not assign a base score to vulnerabilities with an Attack Vector of Physical. This is a known limitation of the CVSS framework, which is designed primarily for network-accessible vulnerabilities. The actual risk to an organization with physically accessible devices is high.

EPSS Interpretation: The EPSS probability of 0.0% means that there is no observed exploitation activity in the wild. This is expected for a vulnerability that requires physical access and was only recently published.

Historical Comparison: This vulnerability is similar to other hardware-level UART access issues, such as:

• CVE-2019-13101 (D-Link DIR-890L): Exposed UART interface allowing root shell access.
• CVE-2020-15482 (TP-Link Archer A7): Unauthenticated UART access leading to full device compromise.

These CVEs share the same CWE category (CWE-1192: System-on-Chip (SoC) Improper Access Control) and attack vector (physical UART access).

Temporal and Environmental Scores:

• Temporal Score: Not calculated due to lack of exploit code and patch.
• Environmental Score: Organizations with devices in secure, access-controlled environments can reduce the environmental score to Low. Organizations with devices in public, unattended locations should consider the environmental score as High.

Technical Deep Dive & Attack Mechanics

Step-by-Step Technical Explanation:

1. Physical Access: The attacker gains physical access to the Autel Maxi Charger Single device.
2. UART Interface Identification: The attacker locates the UART interface on the device's printed circuit board (PCB). This typically consists of four pins: TX (transmit), RX (receive), VCC (power), and GND (ground). The pins are often unpopulated or exposed on a header.
3. Connection: The attacker connects a USB-to-UART adapter (e.g., FTDI, CP2102) to the UART pins. The adapter is then connected to a laptop or other serial terminal device.
4. Boot Interruption: The attacker powers on the device and monitors the serial console output. During the boot process, the U-Boot bootloader presents a countdown timer (e.g., "Hit any key to stop autoboot"). The attacker presses a key to interrupt the normal boot process.
5. U-Boot Shell Access: The attacker is dropped into the U-Boot command-line interface. From here, they can execute commands to:
   • Modify boot arguments (setenv bootargs).
   • Load a custom kernel or root filesystem (tftp, fatload).
   • Read/write to flash memory (sf probe, sf read, sf write).
   • Reset the device (reset).
6. Operating System Access: By modifying the boot configuration to boot into a custom initramfs or by mounting the existing root filesystem, the attacker can gain a root shell on the device's Linux operating system.

Root Cause Analysis: The developer failed to disable or password-protect the UART console in the production firmware. The U-Boot bootloader was compiled with the CONFIG_SYS_CONSOLE_IS_IN_ENV and CONFIG_SILENT_CONSOLE options likely not set to disable the serial console. Additionally, the boot process was not configured to require authentication before entering the U-Boot shell.

Attack Surface:

• Physical: The exposed UART pins on the PCB.
• Logical: The U-Boot bootloader's serial console.

Pre-conditions:

• Physical access to the device.
• A USB-to-UART adapter and a computer with serial terminal software (e.g., PuTTY, screen, minicom).
• Knowledge of the UART baud rate (typically 115200 or 57600 bps).

Attack Variants:

• Boot Argument Manipulation: The attacker can modify the bootargs environment variable to set init=/bin/sh, which will drop them into a shell immediately after the kernel boots.
• File System Modification: The attacker can use U-Boot commands to read the existing root filesystem from flash, modify it (e.g., add a backdoor user, change passwords), and write it back.
• Custom Firmware Flashing: The attacker can load a completely custom firmware image via TFTP or from a USB drive.

Why Standard Defenses May Fail:

• Network Firewalls: UART access is a physical interface, so network-based firewalls are irrelevant.
• Authentication: The UART console requires no authentication.
• Antivirus/EDR: These tools run within the operating system and cannot protect against bootloader-level attacks.
• Secure Boot: If Secure Boot is not implemented or is misconfigured, the attacker can load unsigned code.

Vulnerable vs. Patched Code Analysis

Vulnerable Code (U-Boot Configuration):

The vulnerability is not in a specific line of code but in the build configuration of the U-Boot bootloader. The vulnerable configuration likely includes:

// In include/configs/autel_maxi_charger.h or similar
#define CONFIG_BOOTDELAY 3
#define CONFIG_BOOTCOMMAND "run autel_bootcmd"
// UART console is enabled by default
// No password protection for the console

Patched Code (Hypothetical):

A patch would involve one or more of the following changes:

1. Disable UART Console:

   #undef CONFIG_SYS_CONSOLE_IS_IN_ENV
   #define CONFIG_SILENT_CONSOLE
   

2. Add Password Protection:

   #define CONFIG_AUTOBOOT_KEYED
   #define CONFIG_AUTOBOOT_PROMPT "Enter password to stop autoboot: "
   #define CONFIG_AUTOBOOT_ENCRYPTED
   #define CONFIG_AUTOBOOT_DELAY_STR "password_hash"
   

3. Enable Secure Boot:

   #define CONFIG_FIT_SIGNATURE
   #define CONFIG_RSA
   

Why the Fix is Sufficient: Disabling the UART console or requiring a password prevents an attacker from interrupting the boot process and accessing the U-Boot shell. Secure Boot ensures that only signed firmware images can be loaded, preventing the attacker from booting a custom kernel.

Regression Considerations: Disabling the UART console will make debugging and field updates more difficult for authorized technicians. A secure, authenticated mechanism (e.g., SSH over a management network) should be provided as an alternative.

Timeline & Disclosure History

• CVE Publication Date: 2026-07-21T21:21:50.327Z
• Estimated Discovery Timeline: Unknown. The vulnerability was likely discovered by a security researcher or penetration tester during a hardware assessment.
• Disclosure Process: The CVE was published by the NVD. No information is available about coordination with Autel.
• Known Exploitation in the Wild: No known active exploitation as of 2026-07-22.
• CISA KEV Addition Date: Not applicable.

Threat Intelligence Context

Threat Actor Profile: This vulnerability is most likely to be exploited by:

• Physical Penetration Testers: Hired to assess the security of EV charging infrastructure.
• Vandals: Individuals seeking to disrupt charging services.
• Competitors: Other EV charging companies attempting to gain a competitive advantage by reverse-engineering Autel's hardware.
• Nation-State Actors: In a targeted campaign against critical energy infrastructure.

Attack Campaign Context: No specific campaigns are known to be exploiting this CVE.

Geographic Targeting Patterns: Any region with deployed Autel Maxi Charger Single devices.

Industry Verticals Most at Risk:

• Electric Vehicle Charging: The primary affected industry.
• Energy & Utilities: Charging stations are part of the energy grid.
• Hospitality & Retail: Hotels, shopping malls, and parking garages that offer EV charging as an amenity.

Connection to Similar Vulnerability Classes: This is a classic example of an exposed debug interface (CWE-1192). Similar vulnerabilities have been found in routers, IoT devices, and industrial controllers.

Exploitation & Lab Setup

Red Team Section:

Lab Setup:

1. Hardware:
   • Autel Maxi Charger Single (firmware V1.03.51 or earlier).
   • USB-to-UART adapter (e.g., FTDI FT232RL).
   • Jumper wires.
   • Laptop with serial terminal software (e.g., PuTTY, screen).
2. Software:
   • screen (Linux/macOS) or PuTTY (Windows).
   • minicom (Linux).

Prerequisites:

• Physical access to the device.
• Ability to open the device enclosure (may require special tools).

Exploitation Walkthrough:

1. Open the Device: Remove the screws and open the enclosure to access the main PCB.
2. Identify UART Pins: Look for a 4-pin header labeled "UART", "DEBUG", or "J1". If unlabeled, use a multimeter to identify GND (continuity to ground) and VCC (3.3V).
3. Connect the Adapter:
   • Connect GND to GND.
   • Connect TX (adapter) to RX (device).
   • Connect RX (adapter) to TX (device).
   • Do not connect VCC unless you are sure the device provides power to the header.
4. Open Serial Terminal:

   screen /dev/ttyUSB0 115200
   

5. Power On the Device: Observe the boot log.
6. Interrupt Boot: When prompted ("Hit any key to stop autoboot"), press a key (e.g., Enter, Space).
7. U-Boot Shell: You should see a => prompt.
8. Gain OS Access:

   # Set boot arguments to drop into a shell
   setenv bootargs console=ttyS0,115200 init=/bin/sh
   # Boot the device
   boot
   

9. Post-Exploitation: You now have a root shell. You can:
   • Mount the root filesystem: mount -t jffs2 /dev/mtdblockX /mnt
   • Add a user: echo "backdoor:$6$...:0:0:root:/root:/bin/sh" >> /mnt/etc/passwd
   • Modify configuration files.
   • Extract sensitive data.

Expected Output:

• Successful interruption of the boot process.
• Access to the U-Boot command line.
• A root shell on the device.

Post-Exploitation:

• Persistence: Add a cron job or modify the init scripts to start a reverse shell.
• Lateral Movement: Scan the internal network for other devices.
• Data Exfiltration: Extract charging logs, user data, and payment information.

Blue Team Section:

How to Detect Active Exploitation Attempts:

• Physical Inspection: Look for signs of tampering (e.g., opened enclosure, connected wires, foreign objects).
• Serial Console Logs: If the device logs serial console activity, look for unexpected U-Boot commands or boot interruptions.
• Network Anomalies: After exploitation, the device may exhibit unusual network behavior (e.g., connections to unknown IPs, data exfiltration).

Log Entries That Indicate Exploitation:

• System logs showing unexpected reboots or boot failures.
• Kernel logs indicating a change in the init process.
• Authentication logs showing new user accounts.

Network Traffic Signatures:

• TFTP traffic from the device to an unknown server (if the attacker loads a custom image via TFTP).
• SSH or reverse shell traffic from the device to an external IP.

Endpoint Behavioral Indicators:

• Unexpected processes running as root.
• Modified system binaries or configuration files.
• Presence of new user accounts.

Indicators of Compromise (IOCs)

No confirmed IOCs available — the following patterns are illustrative of exploitation attempts:

Network IOCs:

• TFTP Requests: The device may initiate TFTP requests to an attacker-controlled server to download a custom firmware image.
• Reverse Shells: The device may establish outbound connections to an attacker's command-and-control (C2) server on ports 443, 4444, or 8080.

HTTP Request Patterns:

• Not applicable for the initial exploitation (physical access).

File System Artifacts:

• /etc/passwd or /etc/shadow containing unauthorized user entries.
• /etc/crontab or /etc/init.d/ containing malicious startup scripts.
• /root/.ssh/authorized_keys containing an attacker's SSH public key.

Process Execution Anomalies:

• bash, sh, or python processes spawned by unexpected parent processes (e.g., init).
• tftp or wget processes downloading files.

Log Entries:

• dmesg output showing a change in the init process.
• auth.log showing successful logins for new users.

STIX-like IOC List:

Detection Engineering

YARA Rule

rule CVE-2026-8988_Autel_UART_Exploitation {
    meta:
        description = "Detects exploitation of CVE-2026-8988 in Autel Maxi Charger Single via UART boot interruption"
        author = "Valters IT Hub"
        date = "2026-07-22"
        reference = "https://www.valtersit.com/cve/cve-2026-8988"
    strings:
        $uboot_prompt = "=> " ascii wide nocase
        $boot_interrupt = "Hit any key to stop autoboot" ascii wide nocase
        $setenv_bootargs = "setenv bootargs" ascii wide nocase
        $init_shell = "init=/bin/sh" ascii wide nocase
    condition:
        any of ($uboot_prompt, $boot_interrupt) and 1 of ($setenv_bootargs, $init_shell)
}

Sigma Rule (SIEM)

title: CVE-2026-8988 Autel UART Exploitation Detection
id: d8677fb2-3cc7-4191-ada4-caa01972a9c2
status: experimental
description: Detects exploitation attempts targeting CVE-2026-8988 in Autel Maxi Charger Single via UART boot interruption
author: Valters IT Hub
date: 2026-07-22
references:
    - https://www.valtersit.com/cve/cve-2026-8988
logsource:
    category: process_creation
    product: linux
detection:
    selection:
        ParentImage|endswith: '/init'
        Image|endswith: '/bin/sh'
    condition: selection
falsepositives:
    - Legitimate administrative activity via serial console
level: high

Suricata IDS Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET 69 (msg:"CVE-2026-8988 Autel TFTP Firmware Download"; content:"|00 01|"; depth:2; offset:0; content:"firmware.bin"; nocase; classtype:attempted-admin; sid:1000001; rev:1;)

Elastic (EQL) Query

process where event.type == "start" and process.parent.name == "init" and process.name in ("sh", "bash", "dash")

Splunk SPL Query

index=linux_secure sourcetype=linux_secure parent_process=init process_name IN ("sh", "bash", "dash")

Wazuh Rule

<group name="autel,exploitation,">
  <rule id="100001" level="12">
    <if_sid>550</if_sid>
    <field name="process.name">^(sh|bash|dash)$</field>
    <field name="process.ppid">1</field>
    <description>CVE-2026-8988: Possible Autel UART exploitation - shell spawned by init</description>
    <group>autel_exploitation,</group>
  </rule>
</group>

Remediation & Mitigation

Immediate Actions (0-24 hours):

• Physical Security: Ensure all Autel Maxi Charger Single devices are in physically secure locations (e.g., locked enclosures, monitored areas).
• Tamper Detection: Implement tamper-evident seals on device enclosures.
• Network Segmentation: Place charging stations on a separate VLAN with strict egress filtering.

Short-term (1-7 days):

• Configuration Hardening: If possible, disable the UART console in the device's firmware configuration (requires vendor support).
• Monitoring: Implement the detection rules provided in this report to monitor for post-exploitation activity.
• Vulnerability Scanning: Use a hardware security assessment tool to check for exposed UART interfaces.

Long-term:

• Vendor Patch: Await a firmware update from Autel that disables or password-protects the UART console.
• Architecture Changes: Design future deployments with secure boot and hardware security modules (HSMs).
• Developer Training: Educate hardware engineers on the risks of exposed debug interfaces.

Validation:

• Physical Inspection: Visually confirm that the UART header is not accessible.
• Firmware Version Check: Confirm that the device is running a patched firmware version (once available).
• Boot Test: Attempt to interrupt the boot process via UART to verify the fix.

References & Resources

• NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-8988
• CVE.org: https://www.cve.org/CVERecord?id=CVE-2026-8988
• Vendor advisory: See Autel security page
• OSV: https://osv.dev/vulnerability/CVE-2026-8988
• Related CWE: https://cwe.mitre.org/data/definitions/1192.html
• MITRE ATT&CK: https://attack.mitre.org/techniques/T1200/

Report generated by Valters IT Hub Neural Engine v25 | 2026-07-22 | https://www.valtersit.com/cve/cve-2026-8988