CVE-2026-4036: Synology DiskStation Manager SQL Injection

CVE-2026-4036 Overview

CVE-2026-4036 is a SQL injection vulnerability in the Sharing API component of Synology DiskStation Manager (DSM). The flaw allows remote authenticated users to obtain arbitrary sharing files by injecting crafted SQL syntax into API requests. Synology addressed the issue in DSM 7.2.1-69057-10, 7.2.2-72806-7, and 7.3.2-86009-2. The weakness is tracked as CWE-89: Improper Neutralization of Special Elements used in an SQL Command. The vulnerability requires authentication but no user interaction, and it is exploitable across the network against exposed DSM instances.

Critical Impact
Authenticated remote attackers can retrieve arbitrary shared files from vulnerable Synology DSM systems, exposing confidential data stored on network-attached storage.

Affected Products

Synology DiskStation Manager (DSM) versions before 7.2.1-69057-10
Synology DiskStation Manager (DSM) versions before 7.2.2-72806-7
Synology DiskStation Manager (DSM) versions before 7.3.2-86009-2

Discovery Timeline

2026-09-18 - CVE-2026-4036 published to the National Vulnerability Database (NVD)
2026-09-18 - Last updated in NVD database

Technical Details for CVE-2026-4036

Vulnerability Analysis

The vulnerability resides in the Sharing API of Synology DSM, the web-facing subsystem that manages file sharing links and permissions. Input passed to the API is concatenated into SQL statements without proper neutralization of special characters. An authenticated attacker crafts request parameters that break out of the intended SQL query context. The database then executes attacker-controlled clauses against tables that catalog shared files. The result is unauthorized read access to sharing records that the account should not be able to enumerate or retrieve.

The attack requires network reachability to the DSM web interface and valid low-privilege credentials. No user interaction is needed to trigger exploitation. Confidentiality is directly affected; integrity and availability of the underlying system are not impacted by this specific flaw.

Root Cause

The root cause is improper neutralization of user-supplied input within a SQL query built by the Sharing API. Parameterized queries or strict input validation were not applied to at least one code path handling sharing lookups. This is a classic instance of CWE-89, where dynamic SQL construction trusts caller-provided data.

Attack Vector

An attacker authenticates to a target DSM instance using any valid account, including a low-privileged user. The attacker then issues HTTP requests to the vulnerable Sharing API endpoint with payloads that alter the underlying SQL query. Successful exploitation returns metadata or contents of shared files that the account is not authorized to view. Refer to the Synology Security Advisory SA-26-06 for vendor-supplied technical details.

No public proof-of-concept exploit code has been published for CVE-2026-4036 at the time of writing. The EPSS score is 0.445% (percentile 36.049), indicating a low modeled probability of exploitation in the next 30 days.

Detection Methods for CVE-2026-4036

Indicators of Compromise

Unexpected HTTP requests to DSM Sharing API endpoints containing SQL meta-characters such as single quotes, UNION, SELECT, or comment sequences (--, /*).
Access to sharing files or download links by user accounts that do not own the resources and were not granted explicit permissions.
Bursts of authenticated Sharing API requests originating from a single low-privileged account or IP address.

Detection Strategies

Enable DSM web access logging and forward logs to a centralized platform to identify anomalous query strings against Sharing API URLs.
Deploy signatures on web application firewalls or reverse proxies fronting DSM to flag SQL injection patterns targeting DSM endpoints.
Correlate authentication events with subsequent file access events to detect accounts touching resources outside their normal scope.

Monitoring Recommendations

Track DSM version inventory and alert when systems remain below 7.2.1-69057-10, 7.2.2-72806-7, or 7.3.2-86009-2.
Monitor for successful downloads of shared files immediately following malformed API requests from the same session.
Review DSM audit logs for unusual sharing enumeration activity by non-administrative users.

How to Mitigate CVE-2026-4036

Immediate Actions Required

Upgrade DSM to 7.2.1-69057-10, 7.2.2-72806-7, or 7.3.2-86009-2 (or later) on all affected appliances.
Audit existing DSM user accounts and disable inactive or unnecessary credentials to reduce the authenticated attack surface.
Restrict DSM web interface exposure to trusted networks or VPN-accessible ranges where feasible.

Patch Information

Synology released fixed builds in DSM 7.2.1-69057-10, 7.2.2-72806-7, and 7.3.2-86009-2. Administrators should apply the update through the DSM Control Panel or the vendor download portal. Full remediation guidance is available in the Synology Security Advisory SA-26-06.

Workarounds

Enforce strong authentication, including two-factor authentication, on all DSM accounts to raise the barrier for the authenticated attacker prerequisite.
Place DSM behind a web application firewall configured with SQL injection rule sets until patching is complete.
Limit sharing functionality to a minimal set of trusted users and disable the Sharing API for accounts that do not require it.

bash

# Verify current DSM version from the shell (admin SSH session)
cat /etc.defaults/VERSION

# Confirm build meets or exceeds a fixed release, for example:
# productversion="7.2.2"
# buildnumber="72806"
# smallfixnumber="7"