CVE-2026-2237: Synology Storage Manager Vulnerability

CVE-2026-2237 Overview

CVE-2026-2237 is an information disclosure vulnerability in the volume encryption feature of Synology Storage Manager. The flaw stems from the use of HTTP GET requests with sensitive query strings, which expose confidential data through logs, browser history, and intermediary systems. Synology Storage Manager versions before 1.0.1-1100 are affected. Local attackers can exploit this weakness to obtain sensitive information such as encryption parameters or credentials handled by the volume encryption workflow. The issue is tracked under CWE-598: Use of GET Request Method With Sensitive Query Strings.

Critical Impact

Local attackers with access to the affected system can retrieve sensitive volume encryption data passed through GET request query strings, potentially compromising encrypted storage confidentiality.

Affected Products

• Synology Storage Manager package versions prior to 1.0.1-1100
• Synology DiskStation Manager (DSM) environments running the vulnerable Storage Manager package
• Synology NAS appliances utilizing volume encryption features through Storage Manager

Discovery Timeline

• 2026-05-27 - CVE-2026-2237 published to NVD
• 2026-05-27 - Last updated in NVD database
• Vendor Advisory - Synology Security Advisory SA-26-01 published

Technical Details for CVE-2026-2237

Vulnerability Analysis

The vulnerability resides in the volume encryption component of Synology Storage Manager. The application transmits sensitive data, such as encryption keys or passphrases, as query string parameters in HTTP GET requests. GET request parameters are persisted in multiple locations including web server access logs, browser history, proxy logs, and referer headers sent to third-party resources. This violates the principle that sensitive data should be transmitted in request bodies using POST methods over secured channels.

A local attacker who can read these logs or access browser artifacts on the appliance can recover the sensitive parameters. The weakness aligns with CWE-598, which describes improper handling of sensitive information in URL query strings. The EPSS probability is reported at 0.008%.

Root Cause

The root cause is an insecure design decision in the Storage Manager web interface. Developers used the HTTP GET method to transport volume encryption parameters that should have been sent as form data in POST request bodies. Query string contents are systematically logged by web servers and operating systems, creating durable copies of sensitive material outside the application's protective boundary.

Attack Vector

Exploitation requires local access to the Synology appliance or to systems that store related logs. An attacker with shell access, log reading permissions, or access to browser history on administrative workstations can extract the query string values. No authentication is required to read previously logged entries if the attacker holds the necessary file system permissions on stored log artifacts. User interaction is not required.

The vulnerability is not remotely exploitable on its own and requires local positioning. No public exploit code is available, and the issue is not listed in the CISA Known Exploited Vulnerabilities catalog.

Detection Methods for CVE-2026-2237

Indicators of Compromise

• Web server access logs on the Synology appliance containing GET requests to Storage Manager volume encryption endpoints with parameter values resembling passphrases or key material
• Unexpected access by non-administrative local users to DSM log directories or Storage Manager configuration paths
• Browser history entries on administrator workstations showing encryption-related URLs with embedded query parameters

Detection Strategies

• Audit installed Storage Manager package versions across the fleet and flag any instance below 1.0.1-1100
• Review historical web server and reverse proxy access logs for GET requests to volume encryption URIs that include sensitive parameter names
• Correlate local account activity with access to DSM log files to identify unauthorized reads of stored request logs

Monitoring Recommendations

• Enable verbose audit logging on Synology appliances and forward logs to a centralized SIEM for long-term retention and analysis
• Monitor file integrity and read access on DSM web log directories to detect reconnaissance against historical request data
• Track Storage Manager package version inventory through configuration management to identify unpatched systems quickly

How to Mitigate CVE-2026-2237

Immediate Actions Required

• Upgrade the Synology Storage Manager package to version 1.0.1-1100 or later through DSM Package Center
• Rotate any volume encryption passphrases or keys that may have been submitted through the vulnerable interface prior to patching
• Purge historical web server access logs and administrator browser history that may contain previously transmitted encryption parameters
• Restrict local shell and log directory access on Synology appliances to a minimal set of trusted administrators

Patch Information

Synology has released a fixed Storage Manager package, version 1.0.1-1100, which resolves the insecure GET request handling. Refer to the Synology Security Advisory SA-26-01 for vendor-confirmed remediation guidance and complete affected version details.

Workarounds

• Limit administrative access to DSM and Storage Manager interfaces to dedicated management workstations with disciplined browser history controls
• Restrict read permissions on web server log directories to root or equivalent privileged accounts only
• Avoid performing volume encryption configuration changes on unpatched systems until the update has been applied