CVE-2026-28718: Acronis Cyber Protect DoS Vulnerability

CVE-2026-28718 Overview

CVE-2026-28718 is a denial of service vulnerability affecting Acronis Cyber Protect 17 on Linux and Windows platforms. The flaw stems from insufficient input validation within the authentication logging component, allowing remote attackers to disrupt service availability without requiring authentication or user interaction.

Critical Impact

Remote attackers can exploit this vulnerability to cause a denial of service condition in Acronis Cyber Protect 17, potentially disrupting backup and data protection operations across enterprise environments.

Affected Products

• Acronis Cyber Protect 17 (Linux) before build 41186
• Acronis Cyber Protect 17 (Windows) before build 41186

Discovery Timeline

• 2026-03-06 - CVE CVE-2026-28718 published to NVD
• 2026-03-12 - Last updated in NVD database

Technical Details for CVE-2026-28718

Vulnerability Analysis

This vulnerability is classified under CWE-779 (Logging of Excessive Data), indicating that the authentication logging mechanism fails to properly validate or limit input data before processing. The flaw can be exploited remotely over the network with low attack complexity, requiring no privileges or user interaction.

The vulnerability specifically affects the authentication logging subsystem of Acronis Cyber Protect 17. When specially crafted input is submitted during authentication operations, the logging component processes the data without adequate validation, leading to resource exhaustion and service disruption. The impact is isolated to availability, with no direct effect on confidentiality or integrity of the protected systems.

Root Cause

The root cause is insufficient input validation in the authentication logging functionality. The logging mechanism accepts and processes authentication-related data without properly sanitizing or limiting the input, allowing attackers to submit malicious payloads that trigger excessive logging operations or resource consumption.

Attack Vector

The attack vector is network-based, allowing remote exploitation. An unauthenticated attacker can send specially crafted authentication requests to the Acronis Cyber Protect service. When these requests are processed by the vulnerable logging component, the insufficient validation allows for denial of service conditions to occur.

The attack does not require any special privileges or user interaction, making it particularly dangerous in environments where the Acronis Cyber Protect service is exposed to untrusted networks. The logging of excessive data during authentication attempts can lead to disk space exhaustion, memory consumption, or CPU saturation.

Detection Methods for CVE-2026-28718

Indicators of Compromise

• Unusual spikes in authentication log file sizes or growth rates
• Excessive disk I/O operations related to Acronis Cyber Protect logging processes
• Service unavailability or degraded performance of Acronis Cyber Protect components
• Abnormal authentication request patterns from external or unexpected IP addresses

Detection Strategies

• Monitor Acronis Cyber Protect service availability and response times for anomalies
• Implement network traffic analysis to detect unusual authentication request volumes or patterns
• Configure alerting on rapid log file growth in Acronis Cyber Protect logging directories
• Deploy intrusion detection signatures targeting malformed authentication requests

Monitoring Recommendations

• Enable resource usage monitoring (CPU, memory, disk I/O) for Acronis Cyber Protect processes
• Set up log rotation and size limits to mitigate impact of excessive logging
• Monitor network connections to Acronis Cyber Protect services for anomalous traffic patterns
• Implement centralized log aggregation to detect attack patterns across multiple endpoints

How to Mitigate CVE-2026-28718

Immediate Actions Required

• Update Acronis Cyber Protect 17 to build 41186 or later on all affected Linux and Windows systems
• Restrict network access to Acronis Cyber Protect services to trusted IP ranges only
• Enable rate limiting on authentication endpoints where possible
• Monitor for signs of exploitation while patches are being deployed

Patch Information

Acronis has released a security update addressing this vulnerability in Acronis Cyber Protect 17 build 41186. Organizations should apply this update immediately to remediate the denial of service risk. For detailed patch information and download instructions, refer to the Acronis Security Advisory SEC-8377.

Workarounds

• Implement network segmentation to limit exposure of Acronis Cyber Protect services to untrusted networks
• Configure firewall rules to restrict access to Acronis Cyber Protect authentication endpoints
• Enable log rotation and set maximum log file sizes to reduce impact of excessive logging attacks
• Consider deploying a web application firewall (WAF) or reverse proxy with input validation capabilities in front of exposed services

# Configuration example - Restrict network access to Acronis services
# Example iptables rule to limit access to trusted networks only
iptables -A INPUT -p tcp --dport 9877 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 9877 -j DROP

# Example log rotation configuration for Acronis logs
# Add to /etc/logrotate.d/acronis
/var/log/acronis/*.log {
    daily
    rotate 7
    maxsize 100M
    compress
    missingok
    notifempty
}