2.6.0

This is a security release to address potential denial of service attacks when parsing specially crafted,
malicious input from untrusted sources (like user input). See GHSA-c2pc-g5qf-rfrf for more details.

Added

• Added max_delimiters_per_line config option to prevent denial of service attacks when parsing malicious input
• Added table/max_autocompleted_cells config option to prevent denial of service attacks when parsing large tables
• The AttributesExtension now supports attributes without values (#985, #986)
• The AutolinkExtension exposes two new configuration options to override the default behavior (#969, #987):
  • autolink/allowed_protocols - an array of protocols to allow autolinking for
  • autolink/default_protocol - the default protocol to use when none is specified
• Added RegexHelper::isWhitespace() method to check if a given character is an ASCII whitespace character
• Added CacheableDelimiterProcessorInterface to ensure linear complexity for dynamic delimiter processing
• Added Bracket delimiter type to optimize bracket parsing

Changed

• [ and ] are no longer added as Delimiter objects on the stack; a new Bracket type with its own stack is used instead
• UrlAutolinkParser no longer parses URLs with more than 127 subdomains
• Expanded reference links can no longer exceed 100kb, or the size of the input document (whichever is greater)
• Delimiters should always provide a non-null value via DelimiterInterface::getIndex()
  • We'll attempt to infer the index based on surrounding delimiters where possible
• The DelimiterStack now accepts integer positions for any $stackBottom argument
• Several small performance optimizations