Security fixes in thephpleague/commonmark parser: URL validation and DoS mitigation

Vulnerability Overview This vulnerability involves a二次 attack (second-order attack) in Markdown parsing. Attackers can construct specific Markdown inputs that cause the parser to exhibit abnormal behavior during processing, potentially leading to security risks. Impact Scope Affected Component: Markdown parser Affected Versions: Specific versions are not explicitly mentioned, but according to the commit records, this vulnerability exists in the library. Potential Risks: May cause parser crashes, information leakage, or other security vulnerabilities. Remediation Plan 1. Code Modifications: - In the file, the method was modified to add validation checks for URL validity, avoiding further processing of invalid URLs. - In the file, the method was optimized to ensure that multi-byte characters are not scanned repeatedly, improving parsing efficiency. - In the file, additional test cases were added to ensure parser stability under extreme conditions. - In the file, multiple test cases were added to cover various edge cases and abnormal inputs. - In the file, multiple test cases were added to ensure correct handling of multi-byte and special characters. - In the file, multiple test cases were added to ensure correct handling of complex Markdown syntax. 2. Test Coverage: - Added multiple test cases to ensure the patched parser functions correctly under various conditions. - Test cases cover multi-byte characters, special characters, and edge cases to ensure parser robustness. POC Code Below are some POC code examples: The above code demonstrates the key patched sections and test cases, ensuring that the parser functions correctly under various input conditions.

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Security fixes in thephpleague/commonmark parser: URL validation and DoS mitigation

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