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5 PDF Security Mistakes You’re Probably Making Right Now

Sending sensitive documents as unprotected PDFs is a serious security risk. Here are the 5 most common PDF security mistakes and how to fix them.

March 1, 2026 · 2 min read

PDFs are the standard format for sensitive documents — contracts, financial statements, medical records, legal filings. Yet most people send them with zero security. Here are the five mistakes that put your documents at risk.

1. Sending Sensitive PDFs Without a Password

An unprotected PDF is a plain text file that anyone who intercepts it can read. If you’re sending contracts, financial data, or any confidential information, add a password before you send.

PDFRun’s Protect PDF tool adds 256-bit AES encryption in seconds. The recipient needs the password to open it — without it, the file is unreadable.

2. Using Weak Passwords

A password of “1234” or “password” provides no real protection. For sensitive documents, use a password that’s at least 12 characters and includes a mix of letters, numbers, and symbols. Send the password via a different channel (SMS, phone call) rather than the same email as the PDF.

3. Forgetting to Redact Before Sharing

Blacking out text with a black rectangle is not redaction — it’s just covering. The text underneath is still in the file and can be revealed by changing the color or copying the text. True redaction permanently removes the underlying content.

Use PDFRun’s Redact PDF tool to permanently remove sensitive information before sharing.

4. Ignoring Document Metadata

PDFs contain hidden metadata — author name, company, software used, revision history, and sometimes even content that was “deleted” but not properly removed. Before sending external documents, strip the metadata.

5. Uploading to Untrustworthy Online Tools

Many free PDF tools store your files permanently, use them for training AI models, or sell data to third parties. Always check the privacy policy before uploading sensitive documents.

PDFRun deletes all files within 1 hour of processing. No exceptions, no data retention, no sharing. Your documents stay private.

Quick Security Checklist

Before sending any sensitive PDF: ☐ Password protected? ☐ Sensitive text properly redacted? ☐ Metadata stripped? ☐ Uploaded to a trusted tool only?

Takes 5 minutes. Worth it every time.

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