Mortal sins can absolutely be forgiven in Catholicism

See for example the Catechism of the Catholic Church 1456

> 1456

> Confession to a priest is an essential part of the sacrament of Penance: "All mortal sins of which penitents after a diligent self-examination are conscious must be recounted by them in confession, even if they are most secret and have been committed against the last two precepts of the Decalogue; for these sins sometimes wound the soul more grievously and are more dangerous than those which are committed openly.

That seems to say mortal sins must be confessed. But I cannot see where it says they can be forgiven.

The only unforgivable sin according to the Church is "blasphemy against the Holy Spirit"[1], which is defined as refusal of God's mercy and forgiveness [2].

[1]: https://ucatholic.com/catechism/1864/

[2]: https://www.vatican.va/content/john-paul-ii/en/encyclicals/d... (see 46)

Your references seem to say that blasphemy is unforgivable but not that other mortal sins are forgivable. Unless I’m missing something.