CVE-2026-28726: Acronis Cyber Protect Info Disclosure

CVE-2026-28726 Overview

CVE-2026-28726 is a sensitive information disclosure vulnerability affecting Acronis Cyber Protect 17 on Linux and Windows platforms. The vulnerability stems from improper access control mechanisms that allow authenticated users to access sensitive information they should not be authorized to view. This security flaw exists in versions prior to build 41186.

Critical Impact

Authenticated attackers can exploit this improper access control vulnerability to gain unauthorized access to sensitive information, potentially exposing confidential data within the Acronis Cyber Protect environment.

Affected Products

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

Discovery Timeline

• 2026-03-06 - CVE-2026-28726 published to NVD
• 2026-03-09 - Last updated in NVD database

Technical Details for CVE-2026-28726

Vulnerability Analysis

This vulnerability is classified under CWE-863 (Incorrect Authorization), which occurs when software does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action. In the context of Acronis Cyber Protect 17, the improper access control allows authenticated users to retrieve sensitive information that should be restricted based on their authorization level.

The network-based attack vector requires low privileges and no user interaction, making it relatively straightforward to exploit for authenticated attackers within the network. The impact is limited to confidentiality, with no direct effect on integrity or availability of the system.

Root Cause

The root cause of this vulnerability lies in improper access control implementation within Acronis Cyber Protect 17. The application fails to properly validate user authorization levels before granting access to sensitive resources, allowing users with lower privilege levels to access information intended only for higher-privileged accounts or administrators.

Attack Vector

The vulnerability can be exploited over the network by an authenticated attacker with low-level privileges. The attack does not require any user interaction, and the scope remains unchanged (confined to the vulnerable component). An attacker can leverage this flaw to access sensitive configuration data, user information, or other protected resources within the Acronis Cyber Protect management interface.

The exploitation typically involves crafting requests to access protected endpoints or resources without proper authorization checks being enforced by the application.

Detection Methods for CVE-2026-28726

Indicators of Compromise

• Unusual access patterns to sensitive configuration files or data endpoints by low-privileged user accounts
• Unexpected API calls or requests from authenticated users attempting to access resources outside their authorization scope
• Anomalous read operations on sensitive data stores within the Acronis Cyber Protect environment

Detection Strategies

• Monitor authentication and authorization logs for access attempts to privileged resources by non-administrative accounts
• Implement security information and event management (SIEM) rules to detect authorization bypass patterns
• Review access control logs for discrepancies between user privilege levels and accessed resources

Monitoring Recommendations

• Enable verbose logging for access control decisions within Acronis Cyber Protect 17
• Configure alerts for repeated access attempts to sensitive endpoints by users with insufficient privileges
• Regularly audit user permissions and access patterns to identify potential exploitation attempts

How to Mitigate CVE-2026-28726

Immediate Actions Required

• Upgrade Acronis Cyber Protect 17 to build 41186 or later immediately
• Review and audit current user permissions to ensure principle of least privilege
• Monitor access logs for any signs of unauthorized information access prior to patching

Patch Information

Acronis has addressed this vulnerability in Acronis Cyber Protect 17 build 41186. Organizations should update to this version or later to remediate the improper access control issue. For detailed patch information, refer to the Acronis Security Advisory SEC-8401.

Workarounds

• Restrict network access to the Acronis Cyber Protect management interface to trusted IP ranges only
• Implement additional network segmentation to limit exposure of the vulnerable system
• Apply principle of least privilege by reviewing and restricting user account permissions until patches can be applied
• Consider deploying a web application firewall (WAF) to add an additional layer of access control

# Example: Restrict access to Acronis management interface via firewall
# Allow only trusted management network
iptables -A INPUT -p tcp --dport 9877 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 9877 -j DROP