CVE-2023-52081: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

ffcss is a CLI interface to apply and configure Firefox CSS themes. Prior to 0.2.0, the function lookupPreprocess() is meant to apply some transformations to a string by disabling characters in the regex [-_ .]. However, due to the use of late Unicode normalization of type NFKD, it is possible to bypass that validation and re-introduce all the characters in the regex [-_ .]. The lookupPreprocess() can be easily bypassed with equivalent Unicode characters like U+FE4D (?), which would result in the omitted U+005F (_), for instance. The lookupPreprocess() function is only ever used to search for themes loosely (case insensitively, while ignoring dashes, underscores and dots), so the actual security impact is classified as low. This vulnerability is fixed in 0.2.0. There are no known workarounds.