Enemy encounters aren’t the only thing you find in Hollow Knight: Silksong; there are NPCs and quests to close, some of which have puzzles to crack as well. Once you reach Weavenest Cindril, there is a quick puzzle to solve to help you unlock the next region, and this guide explains how to go about doing exactly that.
How to Solve the Weavenest Cindril Puzzle in Silksong
To gain access to the rest of Weavenest Cindril, collect the Flea Brew and the Silkspeed Anklet to gain momentum and run across the entrance passage to Weavenest Cindril. You can collect the Flea Brew from Greymoor and the Silkspeed Anklet at the entrance to Weavenest Cindril.
The Flea Brew takes up a Red slot and increases movement as well as attack speed, making it a pretty useful tool to slot in your Crest.
The Silkspeed Anklets take up a Yellow slot and increase sprint speed by consuming Silk.
How to Get Flea Brew In Silksong

You need to complete the Lost Fleas quest, then walk up to the cauldron beside Fleamaster Mooshka and refill it using 30 Rosaries. If you have completed the quest, then Fleamaster Mooshka would occupy the Purified Ducts area. The cauldron is located just west of the Fleamaster. Collect the Flea Brew from the cauldron once ready.
How to Get Silkspeed Anklets In Silksong

The next step is to head over to Far Fields and travel all the way to the lower section while sticking to the east. You will spot a corridor that takes you to Weavenest Cindril. Go through the level as normal till you reach a blocked passage.
The walls around you will light up if you sprint across the passage as fast as you can. Consuming the Flea Brew from earlier will help you with that. You might have to run through the passage at high speeds several times till something happens. When all the lights are lit up, you will receive the Silkspeed Anklets tool.
Accessing Weavnest Cindril
With these two items in hand, consume the brew at the bench before Weavenest Cindril and also equip the Anklet. Jump back down to the area where you received the anklet the first time and race through the passage. After bumping against the wall at the end of the passage, the floor below will open up, giving you access to the rest of the area.
Before getting to Weavenest Cindril in Hollow Knight Silksong, you would have to pass through The Slab. Within this area, you require several keys, and we have guides on how to get the Key of Indolent, Key of Heretic, and the Key of Apostate, so check them out.