Does Hebrews 10:26-27 speak of another unforgivable sin?

[Steven87]

For if we sin willfully after we have received the knowledge of the truth,
there no longer remains a sacrifice for sins,
but a certain fearful expectation of judgment,
and fiery indignation which will devour the adversaries.
**

To me this passage looks like it is talking about a sin that is not covered by the blood of Jesus and can therefore not be forgiven.
This has been bugging me for a long time, and I have been looking for an answer but unable to get a clear one. I read that God can forgive any sin except those unrepented at death. But to me this passage looks like it’s talking about another unforgivable sin.
what does this passage mean?

 

[Jim_Blackburn]

The only sin that is unforgivable is that which is never repented of – that which one never sincerely seeks forgiveness for. This passage in Hebrews defines mortal sin which, if left un-repented, results in the loss of salvation.

Mortal sin requires grave matter, full knowledge, and deliberate consent (cf. Catechism, 1857). Notice that the author of Hebrews speaks of sinning willfully (deliberate consent) after receiving knowledge of the truth. He goes on (v. 29) to describe the grave matter of which he is writing: spurning the Son of God, profaning the blood of the covenant, and outraging the Spirit of grace. These sins committed with full knowledge and deliberate consent are mortal sins and they will result in the loss of salvation if left un-repented.

See also:
Are any sins unforgivable?
What is “blasphemy against the Holy Spirit” and why is it unforgivable?