Every few years a major PDF redaction failure makes the news. Government secrets, corporate settlements, legal filings — all leaked by black rectangles that turned out to be transparent. A short tour of what happens when people forget that PDF text exists under the bar.
The Mueller report (2019)
Excerpts of the Mueller report released by the DoJ contained redactions applied via overlay rectangles. Researchers extracted the underlying text within hours of release, revealing names and details that were supposed to be hidden.
The fix would have been to use Acrobat's proper Redact tool rather than the Comments rectangle. The cost was real damage to ongoing investigations.
Manafort court filings (2019)
Paul Manafort's lawyers filed redacted court documents that turned out to be reversible. Within minutes of filing, journalists had extracted the hidden content — revealing information about Manafort's contacts with Russian operatives.
The filing went viral as a cautionary tale of legal-tech illiteracy. The information would have come out eventually; the redaction failure made it come out the wrong way.
TSA security manual (2009)
The TSA posted its airport screening manual online with sections redacted via black rectangles. Researchers extracted the hidden text immediately — revealing screening procedures, exempt populations, and other operational details.
The document had to be re-issued. The original was already in circulation and impossible to recall.
Lessons
Three patterns repeat:
1. The redactor doesn't know the rectangle tool is overlay-only. 2. Nobody verifies the redaction before publication by trying to select-and-copy the redacted regions. 3. Time pressure prevents proper review.
For any document where redaction matters, use Flint's redaction tool which removes content rather than covers it, and always verify the output before sharing.
FAQ
Is this still happening in 2026?
Yes. Despite years of public failures, lawyers and government agencies still occasionally release documents with reversible redactions. Tools haven't fully caught up to muscle memory.
What's the most common cause?
Using a generic annotation tool (rectangle, highlight) instead of the dedicated redaction tool. The visual outcome looks the same but the underlying behaviour differs entirely.
Can metadata cause similar leaks?
Yes. Document properties, comments and revision history have all leaked in published PDFs. Strip metadata as part of redaction.
How can I verify my redaction worked?
Try select-and-copy on the redacted regions. If the clipboard is empty, redaction is real. If text appears, it isn't.
Don't join the list of cautionary tales. Redact for real in Flint and verify the output.