Some Microsoft technologies as used in Windows 8 through 11 allow a temporary client-side performance degradation during processing of multiple Unicode combining characters, aka a "Zalgo text" attack. NOTE: third parties dispute whether the computational cost of interpreting Unicode data should be considered a vulnerability.

References

• https://nvd.nist.gov/vuln/detail/CVE-2017-20190
• https://aka.ms/windowsbugbar
• https://en.wikipedia.org/wiki/Zalgo_text
• https://talk.dynalist.io/t/dynalist-is-vulnerable-to-zalgo/1234