{"slug": "one-line-security-fix-how-an-xls-quote-escaping-bug-in-dify-leaked-spreadsheet", "title": "One-Line Security Fix: How an XLS Quote Escaping Bug in Dify Leaked Spreadsheet Data", "summary": "A security researcher identified a CSV injection vulnerability in Dify, an open-source AI platform, where user-supplied cell values in the XLS spreadsheet parser were not properly quoted when written to CSV, allowing crafted values to inject additional rows or columns. The flaw was fixed with a one-line change replacing string concatenation with Python's csv module for proper escaping. The researcher noted that downstream consumers re-importing the exported data could be at risk of data injection into protected fields.", "body_md": "While auditing Dify (an open-source AI platform), I found a one-line bug in the\n\nXLS spreadsheet parser. User-supplied cell values were not properly quoted\n\nwhen written to CSV, allowing specially crafted values to inject additional rows\n\nor columns.\n\nThe original code:\n\n```\n# Vulnerable: no quote escaping\nline = \",\".join(str(cell) for cell in row)\n```\n\nA malicious cell value like `\"evil\",\"data` would break out of the CSV\n\nquoting and inject arbitrary columns. If this CSV was later imported by another\n\nprocess, it could inject data into protected fields.\n\n``` python\n# Fixed: use csv module for proper escaping\nimport csv\nimport io\noutput = io.StringIO()\nwriter = csv.writer(output)\nwriter.writerow(row)\nline = output.getvalue()\n```\n\nCSV injection (also called formula injection) is a common vulnerability in apps\n\nthat export data to spreadsheet formats. Even though the initial export might\n\nseem harmless, downstream consumers that re-import the data are at risk.\n\nThe fix was a single line change — replacing string concatenation with the\n\nproper csv module — but the security impact was significant.\n\n*Follow my bug bounty journey:* [@truongsontung](https://github.com/truongsontung)\n\n*This post is part of my [Autonomous Bug Bounty Hunter](https://dev.to/t/pruongsontung?series=12345) series.*", "url": "https://wpnews.pro/news/one-line-security-fix-how-an-xls-quote-escaping-bug-in-dify-leaked-spreadsheet", "canonical_source": "https://dev.to/truongsontung/one-line-security-fix-how-an-xls-quote-escaping-bug-in-dify-leaked-spreadsheet-data-44pl", "published_at": "2026-09-10 01:09:35+00:00", "updated_at": "2026-09-10 02:19:14.006104+00:00", "lang": "en", "topics": ["ai-products", "ai-tools", "developer-tools"], "entities": ["Dify", "Python"], "alternates": {"html": "https://wpnews.pro/news/one-line-security-fix-how-an-xls-quote-escaping-bug-in-dify-leaked-spreadsheet", "markdown": "https://wpnews.pro/news/one-line-security-fix-how-an-xls-quote-escaping-bug-in-dify-leaked-spreadsheet.md", "text": "https://wpnews.pro/news/one-line-security-fix-how-an-xls-quote-escaping-bug-in-dify-leaked-spreadsheet.txt", "jsonld": "https://wpnews.pro/news/one-line-security-fix-how-an-xls-quote-escaping-bug-in-dify-leaked-spreadsheet.jsonld"}}