hb-ot-layout-gsubgpos.hh in HarfBuzz through 6.0.0 allows attackers to trigger O(n^2) growth via consecutive marks during the process of looking back for base glyphs when attaching marks.
https://security.netapp.com/advisory/ntap-20230725-0006/
https://github.com/harfbuzz/harfbuzz/commit/85be877925ddbf34f74a1229f3ca1716bb6170dc
https://chromium.googlesource.com/chromium/src/+/e1f324aa681af54101c1f2d173d92adb80e37088/DEPS#361