An issue was discovered in the stripTags and unescapeHTML components in Prototype 1.7.3 version 1.6 and below where an attacker can cause a Regular Expression Denial of Service (ReDOS) through stripping crafted HTML tags.

References

• https://nvd.nist.gov/vuln/detail/CVE-2020-27511
• https://github.com/prototypejs/prototype/blob/dee2f7d8611248abce81287e1be4156011953c90/src/prototype/lang/string.js#L283
• https://github.com/yetingli/PoCs/blob/main/CVE-2020-27511/Prototype.md
• http://prototypejs.org/