安全跟踪: NLTK 漏洞缓解路线图

This issue tracks the 20 remaining unfixed NLTK security advisories from Huntr.com, categorized by **shared implementation logic and common code-fixing patterns** to maximize code reuse and streamline Pull Request reviews. These reports were filed near the end of June 2026, so the corresponding CVEs are scheduled for publication in the last week of September.