All versions of lettersanitizer below 1.0.2 are affected by a denial of service issue when processing a CSS at-rule @keyframes.
This package is depended on by react-letter, therefore everyone using react-letter is also at risk.
The problem has been patched in version 1.0.2.
There is no workaround besides upgrading.
The issue was originally reported in the react-letter repository: https://github.com/mat-sz/react-letter/issues/17
If you have any questions or comments about this advisory: * Open an issue in lettersanitizer * Email me at contact@matsz.dev