CVE-2021-41270: Improper Neutralization of Formula Elements in a CSV File

Symfony/Serializer handles serializing and deserializing data structures for Symfony, a PHP framework for web and console applications and a set of reusable PHP components. Symfony is vulnerable to CSV injection, also known as formula injection. In Symfony, maintainers added the opt-in csv_escape_formulas option in the CsvEncoder, to prefix all cells starting with =, +, - or @ with a tab \t. Since then, OWASP added 2 chars in that list: Tab (0x09) and Carriage return (0x0D). This makes the previous prefix char (Tab \t) part of the vulnerable characters, and OWASP suggests using the single quote ' for prefixing the value. Starting with, Symfony now follows the OWASP recommendations and uses the single quote ' to prefix formulas and add the prefix to cells starting by \t, \r as well as =, +, - and @.