YAML
Limiting Alias Expansion in a YAML Parser Across Languages
Where each parser sets its alias limit: SnakeYAML options, Go's built-in check, Ruby's aliases flag, DuckDB's node budget and a PyYAML guard, all tested.
7 min read
Topic
Security
Stop injection, trim privileges, encrypt what matters, and keep the data out of places it should not be.
YAML
Handling YAML Uploads From Users Without Getting Burned
A 40-line guard for accepting YAML uploads: size cap, UTF-8, safe parsing, expanded-size and depth limits, then key checks. Ten test inputs and what each did.
7 min read
Excel
Checking an Excel Upload Before Reading It Into Code
Check an Excel upload before parsing: size, name, zip signature, required parts, macro parts, sheet names and header row, in a fixed order with clear errors.
7 min read
Excel
Password Protected Excel Files and Scripts That Read Them
Read password protected Excel files from a script with msoffcrypto-tool, tell file encryption from sheet protection, and keep passwords out of code and logs.
7 min read
YAML
Secrets Accidentally Committed in YAML Files and the Cleanup
What to do when a token lands in a values or config YAML: removing it from the file leaves it in history, gitleaks finds it, and rotation is the real fix.
6 min read
Excel
Zip Bombs and Oversized XLSX Uploads and Limits That Work
Stop zip bombs and oversized xlsx uploads with limits on file size, entry count, expansion ratio and rows, enforced before parsing and sized from real files.
7 min read
Excel
Opening Untrusted Excel Files Safely in a Pipeline
Open untrusted Excel files in a sandboxed worker with no network, memory and time limits, a read-only parser and no desktop Excel, then load results as data.
7 min read
YAML
Safe Loaders in Python Ruby and Java Compared and Tested
Which function to call in PyYAML, Ruby Psych and SnakeYAML to load untrusted YAML safely, what each default does and how to grep for the unsafe ones.
6 min read
Excel
Removing Personal Data From an Excel File Before Sharing
Remove personal data from an Excel file before sharing: drop author properties, mask or delete columns, clear comments and rebuild a clean copy by script.
7 min read
Excel
Hidden Sheets and Metadata Leaking Out of Shared Workbooks
Find hidden sheets, document properties, comments, defined names and pivot caches in a workbook before you share it, with a script that audits the file.
7 min read
Excel
Macros and Why Data Teams Should Block Them by Default
Compare xlsx, xlsm, xls and xlsb for data work, and set a policy that blocks macros by default while allowing reviewed exceptions with a real owner.
7 min read
YAML
Billion Laughs Style Attacks Through YAML Aliases Tested
Build a 378-byte YAML document that expands to 34 MB, measure PyYAML, DuckDB and Go on it, and see which parsers fail early and which wait for the output.
7 min read
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