As with many words, the meaning depends on context.
The verb blunder means alternatively:
to move in an awkward way
I could hear him blundering around in the darkness.
to make a (serious) mistake, usually because of not taking care or thinking
Police blundered by not releasing more details about the case to focus public interest.
In this case, ...
In this situation according to Longman Dictionary applies definition #1, as a verb:
1 [intransitive always + adverb/preposition] to move in an unsteady way, as if you cannot see properly
Someone was blundering about in the kitchen.
blunder into/past/through etc something:
Phil came blundering down the ...