CVE-2026-76954: Synology DSM SQL Injection

Root Cause

The vulnerability is classified as improper neutralization of special elements used in an SQL command. Input processed by the DSM Auth API is reportedly incorporated into a database operation without sufficient validation, parameterization, escaping, or equivalent protective handling. An attacker who can reach the vulnerable request path may be able to alter the intended SQL operation.

The available vulnerability description does not identify the precise endpoint, parameter name, database engine, authentication flow, or vulnerable code path. Do not guess those details during incident response. Obtain them from Synology’s advisory, vendor technical support, updated NVD data, or authorized reverse engineering.

The stated impact extends beyond ordinary database disclosure. NVD reports that exploitation may permit arbitrary file reads, arbitrary file writes, and denial of service. Those outcomes could result from database-level functionality, application behavior, chained filesystem operations, or a combination of weaknesses. Until the implementation details are confirmed, investigate both database-oriented indicators and unexpected filesystem changes.

Technical Notes

A generic SQL injection pattern can involve unexpected metacharacters or altered request structure, but a generic pattern is not a reliable signature for this CVE. Blocking only a small list of characters is easy to evade and may generate false positives.

Where reverse proxy or web application firewall logging is enabled, preserve the complete request target, query string, HTTP method, response status, response size, source address, and timestamp. A useful initial hunt is for authentication API requests containing SQL control characters or encoded equivalents:

(request.uri.query matches "(?i)(%27|'|%22|\")")
and
(request.uri.query matches "(?i)(union|select|sleep|benchmark|information_schema|or%20[0-9]+=|and%20[0-9]+=)")

This is a triage query, not a vendor-confirmed exploit signature. Validate matches against normal DSM traffic and correlate them with unusual response codes, repeated requests, authentication anomalies, and filesystem events.

Who’s Exposed

The affected product is Synology DiskStation Manager. Based on the available NVD description, affected versions are DSM releases before the following fixed builds:

The available record does not provide a more granular model-specific list. Identify the installed DSM branch and build, then compare it with Synology’s security advisory and the update channel available for the specific NAS model. A system running a later build in the same branch should generally be considered fixed for the stated threshold, but vendor guidance remains authoritative for branch and platform compatibility.

Internet exposure materially increases risk. Prioritize systems with DSM administration or authentication services reachable directly from the public internet, followed by systems reachable from untrusted partner, guest, VPN, or segmented user networks. Internal-only placement reduces exposure but does not eliminate risk, especially where compromised endpoints can reach NAS management interfaces.

Technical Notes

Use DSM’s interface to confirm the installed version, or collect the version through the organization’s approved Synology administration and inventory process. Do not rely solely on the product model number because the same model family may support different DSM branches or update paths.

A basic asset-management record should include:

asset_id
hostname
management_ip
model
installed_dsm_version
internet_exposed
last_successful_update
owner
backup_status

If the installed version is not known, classify the device as potentially vulnerable until its build is verified. Do not infer patch status from an operating system reboot, a successful backup, or a package update unrelated to the DSM base release.

Severity Breakdown

The reported CVSS score is 9.8, classified as Critical. The retrieved NVD record did not provide the CVSS vector, so the exact values for attack vector, attack complexity, privileges required, user interaction, scope, confidentiality, integrity, and availability cannot be stated reliably from the supplied data.

The available description nevertheless indicates a remote attack scenario and significant impact. Arbitrary file reads represent a confidentiality risk, arbitrary file writes represent an integrity risk, and denial of service represents an availability risk. The combination of all three impact categories explains why the vulnerability should receive urgent operational treatment while the exact vector is being confirmed.

Teams should update internal risk records when the complete vector becomes available. Until then, use an exposure-based approach: prioritize public-facing systems, systems containing sensitive data, devices with weak administrative controls, and NAS appliances that cannot be rapidly restored from clean backups.

Exploitation Status

CVE-2026-76954 was not listed in the CISA Known Exploited Vulnerabilities catalog at the time of the supplied review. No CISA date added, due date, required action, or ransomware-campaign flag was returned. The available CISA lookup therefore does not confirm exploitation in the wild.

No public proof-of-concept repository or exploit reference was identified in the reviewed NVD material. The reviewed sources also did not provide confirmed evidence of active exploitation. These are status findings, not guarantees. A vulnerability can be exploited privately, remain absent from CISA KEV, or appear in threat intelligence after a vendor disclosure.

Organizations should use a “no confirmed exploitation, high consequence” posture. Do not delay patching while waiting for a KEV listing or public exploit. If an exposed DSM device shows suspicious requests, unexplained files, authentication anomalies, or service instability, investigate it as a potential compromise rather than treating the absence of public reporting as evidence of safety.

Technical Notes

Preserve evidence before restarting, upgrading, or rebuilding a suspicious appliance when operationally feasible. Collect reverse-proxy logs, firewall records, DSM web and authentication logs, system logs, configuration changes, package inventory, and filesystem timestamps. Maintain the original timestamps and record the collection method.

Look for correlated events rather than a single definitive indicator:

source_ip -> DSM authentication/API endpoint
same source_ip -> repeated malformed or unusually encoded parameters
followed by -> HTTP 2xx/3xx or server errors
followed by -> unexpected file creation/modification or service restart

A SIEM correlation rule can be expressed conceptually as:

count(http_events where product="Synology DSM"
    and uri matches "(?i)(auth|login|api)"
    and request contains SQL-like metacharacters)
by source_ip over 10 minutes > threshold
AND (
    filesystem_write_event on DSM asset
    OR authentication_failure_spike
    OR service_restart
    OR outbound_connection_anomaly
)

The field names will vary by product and collector. Tune the rule against known administrative activity and avoid treating every quote character or failed login as exploitation.

Sources

1. NVD: CVE-2026-76954
   https://nvd.nist.gov/vuln/detail/CVE-2026-76954

2. Synology Security Advisory: Synology_SA_26_19
   https://www.synology.com/en-global/security/advisory/Synology_SA_26_19

3. CISA Known Exploited Vulnerabilities Catalog
   https://www.cisa.gov/known-exploited-vulnerabilities-catalog

The supplied record reports a CVSS score of 9.8 but does not include the complete vector. Confirm the vector and any model-specific applicability directly in the full NVD record and Synology advisory before publishing automated compliance conclusions or applying a one-size-fits-all update procedure.

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