CVE-2026-3276

unicodedata.normalize() can take excessive CPU time when processing specially crafted Unicode input containing long runs of combining characters with alternating Canonical Combining Class values. This affects all normalization forms.

Credits

Seokchan Yoon (https://github.com/ch4n3-yoon)
Tim Peters (https://github.com/tim-one)
Bénédikt Tran (https://github.com/picnixz)
Serhiy Storchaka (https://github.com/serhiy-storchaka)
Stan Ulbrych (https://github.com/StanFromIreland)
Seth Larson (https://github.com/sethmlarson)
Petr Viktorin (https://github.com/encukou)

References