CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
LOW
Availability Impact
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
EPSS
Percentile
17.0%
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 (īš), 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.