// supercookies
what is favicon-cache supercookie?
The 2021 'Supercookie' PoC (jonasstrehle): browsers cached favicons in a SEPARATE store that ignored normal cache clearing and incognito. Redirect through N favicon paths; hit vs miss reads one bit, so N favicons encode an N-bit id that survived a cache clear.. Fast-decaying: browser mitigations land release-to-release; asOf 2026-06-15. Distilled from the richards supercookies catalog.
source capture as of 2026-06-15
in the benchmark
favicon-cache supercookie is tracked as part of the supercookies taxonomy. see how tracked tools score against it on the capability matrix.