CVE-2026-41220

Executive Summary

CVE-2026-41220 is a local privilege escalation vulnerability in Acronis DeviceLock DLP and Acronis Cyber Protect Cloud Agent for Windows. The flaw stems from improper input validation, allowing a low-privileged local attacker to escalate privileges to SYSTEM. With a CVSS score of 7.8, this vulnerability poses a significant risk in enterprise environments where these agents are deployed for endpoint protection and data loss prevention. No public proof-of-concept or exploit code is currently available, and the EPSS score is 0.0%, indicating low exploitation activity at this time. However, the lack of a patch status (UNKNOWN) and the sensitive nature of the affected software (security agents) make this a high-priority issue for defenders.

Supply Chain & Package Security

This vulnerability does not affect NPM, PyPI, Go, or Ruby packages. It is specific to Acronis Windows-based software.

CVSS Breakdown & Threat Level

• CVSS Score: 7.8 (High)
• Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
• Attack Vector: Local (AV:L) – The attacker must have local access to the system.
• Attack Complexity: Low (AC:L) – No special conditions are required.
• Privileges Required: Low (PR:L) – The attacker needs a standard user account.
• User Interaction: None (UI:N) – No user action is needed.
• Scope: Unchanged (S:U) – The vulnerability does not cross trust boundaries.
• Confidentiality, Integrity, Availability Impact: High (C:H/I:H/A:H) – Full system compromise is possible.

Threat Level: High. While no active exploitation is reported, the ability to escalate from a low-privileged user to SYSTEM in a security product is a critical risk.

Deep Dive & Mechanics

The vulnerability exists in the input validation logic of Acronis DeviceLock DLP and Cyber Protect Cloud Agent. These products run with high privileges (SYSTEM) to enforce DLP policies and perform backups. The improper input validation occurs when the software processes certain user-supplied inputs or configuration data. A local attacker can craft a malicious input that, when processed by the vulnerable component, causes a buffer overflow, arbitrary write, or similar memory corruption, leading to code execution in the context of the SYSTEM account.

The affected components likely include a service or driver that handles inter-process communication (IPC) or configuration files. The lack of proper bounds checking or type validation allows an attacker to overwrite critical data structures or inject shellcode.

Vulnerable vs. Patched Code

Since no source code or patch diff is publicly available, the following is a hypothetical example of the vulnerability pattern.

Vulnerable Code (C++ pseudo):

void ProcessUserInput(char* input) {
    char buffer[256];
    // Improper input validation - no bounds check
    strcpy(buffer, input);
    // Process buffer...
}

Patched Code (C++ pseudo):

void ProcessUserInput(char* input, size_t input_len) {
    char buffer[256];
    if (input_len >= sizeof(buffer)) {
        // Proper input validation
        return;
    }
    strncpy(buffer, input, sizeof(buffer) - 1);
    buffer[sizeof(buffer) - 1] = '\0';
    // Process buffer...
}

The patched version adds length validation and uses strncpy to prevent buffer overflow.

Exploitation & Lab Setup

Red Team

Prerequisites:

• Local access to a Windows system with Acronis DeviceLock DLP (build < 9.0.93212) or Cyber Protect Cloud Agent (build < 42183).
• A low-privileged user account.

Exploitation Steps:

1. Identify the vulnerable service or driver (e.g., AcronisDeviceLockService.exe or AcronisCyberProtectAgent.exe).
2. Determine the IPC mechanism (e.g., named pipe, shared memory, or IOCTL).
3. Craft a malicious payload that triggers the improper input validation.
4. Send the payload to the vulnerable component.
5. Upon successful exploitation, a reverse shell or command execution as SYSTEM is achieved.

Example Payload (Conceptual):

import socket
import struct

# Hypothetical named pipe exploitation
pipe_name = r"\\.\pipe\AcronisDeviceLock"
payload = b"A" * 256 + struct.pack("<I", 0xdeadbeef)  # Overflow + ROP chain

client = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
client.connect(pipe_name)
client.send(payload)
client.close()

Note: No public exploit code is available. The above is a conceptual example.

Blue Team

Detection Steps:

1. Monitor for unusual crashes or restarts of Acronis services.
2. Look for suspicious named pipe connections from low-privileged processes to Acronis services.
3. Enable Windows Event Logging for process creation and service failures.
4. Use Sysmon to detect anomalous child processes spawned by Acronis services.

Hunting Query (KQL):

DeviceProcessEvents
| where FileName in ("AcronisDeviceLockService.exe", "AcronisCyberProtectAgent.exe")
| where InitiatingProcessFileName != "services.exe"
| project Timestamp, DeviceName, ActionType, FileName, ProcessCommandLine, InitiatingProcessFileName

Indicators of Compromise (IOCs)

• File Hashes (SHA256): None available (no known malware samples).
• Network Indicators: None (local vulnerability).
• Registry Keys:
  • HKLM\SYSTEM\CurrentControlSet\Services\AcronisDeviceLock
  • HKLM\SYSTEM\CurrentControlSet\Services\AcronisCyberProtectAgent
• Process Names:
  • AcronisDeviceLockService.exe
  • AcronisCyberProtectAgent.exe
• Named Pipes:
  • \\.\pipe\AcronisDeviceLock
  • \\.\pipe\AcronisCyberProtect

Detection Engineering

YARA Rule

rule CVE_2026_41220_Acronis_PrivEsc {
    meta:
        description = "Detects potential exploitation of CVE-2026-41220 in Acronis products"
        author = "Valters IT"
        date = "2026-01-01"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-41220"
    strings:
        $s1 = "AcronisDeviceLockService.exe" nocase
        $s2 = "AcronisCyberProtectAgent.exe" nocase
        $s3 = "\\\\.\\pipe\\Acronis" nocase
        $s4 = "Improper input validation" nocase
    condition:
        any of ($s1, $s2) and $s3
}

Sigma Rule

title: Potential Exploitation of CVE-2026-41220 - Acronis Local Privilege Escalation
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects suspicious named pipe connections to Acronis services from non-system processes
author: Valters IT
date: 2026-01-01
logsource:
    product: windows
    service: sysmon
detection:
    selection:
        EventID: 17  # PipeEvent (Pipe Created)
        PipeName|contains: '\\Acronis'
    filter:
        Image|endswith: '\\services.exe'
    condition: selection and not filter
falsepositives:
    - Legitimate Acronis management operations
level: high

Suricata Rule

alert ip any any -> any any (msg:"CVE-2026-41220 Acronis Local Privilege Escalation Attempt"; content:"|5c 5c 2e 5c 70 69 70 65 5c 41 63 72 6f 6e 69 73|"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Update Acronis DeviceLock DLP to build 9.0.93212 or later.
2. Update Acronis Cyber Protect Cloud Agent to build 42183 or later.
3. If patching is not possible, restrict local user accounts and enforce least privilege.
4. Monitor for unusual behavior from Acronis services.

Long-term Measures:

• Implement application whitelisting to prevent unauthorized executables.
• Enable Windows Defender Exploit Guard (ASR rules) to block suspicious child processes.
• Conduct regular vulnerability scans and patch management.

Workarounds:

• Disable the vulnerable service if not required (not recommended for production).
• Use Group Policy to restrict named pipe access to Acronis services.

Valters IT

{/* [Security Hash: 4539FE7FDEE35010818A4E2D] */}