# Impact of the Prysm invalid signature bug on the mev-boost ecosystem at the Shapella fork

**URL:** https://collective.flashbots.net/t/impact-of-the-prysm-invalid-signature-bug-on-the-mev-boost-ecosystem-at-the-shapella-fork/1623
**Category:** The Flashbots Ship
**Tags:** mev-boost, post-mortem
**Created:** [April 14, 2023, 2:40pm UTC](https://collective.flashbots.net/t/impact-of-the-prysm-invalid-signature-bug-on-the-mev-boost-ecosystem-at-the-shapella-fork/1623 "2023-04-14T14:40:35Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![metachris](https://collective.flashbots.net/user_avatar/collective.flashbots.net/metachris/32/6_2.png) [@metachris](https://collective.flashbots.net/u/metachris)
#### Post date: [April 14, 2023, 2:40pm UTC](https://collective.flashbots.net/t/impact-of-the-prysm-invalid-signature-bug-on-the-mev-boost-ecosystem-at-the-shapella-fork/1623/1 "2023-04-14T14:40:35Z")

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After the Shapella Hardfork, a bug in the code that generates signatures over externally built block headers in Prysm caused invalid signatures to be returned to the `mev-boost` relays. The relays rejected the signature and no block was published during the slot.

A temporary fix was rolled out to the relays as a stop-gap (there’s no more missed slots happening and no further risk to validators), and Prysm has released [v4.0.2](https://github.com/prysmaticlabs/prysm/releases/tag/v4.0.2) which resolves the signing bug. All Prysm node operaters should update to this release asap, to source blocks from the builder network.

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You can find more background, timeline, bug details, patch details and impact in our full write-up at [https://notes.ethereum.org/@mikeneuder/ryJGpiBz2](https://notes.ethereum.org/@mikeneuder/ryJGpiBz2) and the [post-mortem from Prysm here](https://arbitrum.notion.site/17-relayers-are-failing-with-the-prysm-client-post-Capella-Shanghai-2023-04-12-mainnet-0ef5ccd795e54ae4894fa695f1a3e70b).

Huge shoutout to Mike Neuder and the ultra-sound team for the collaboration and shared leadership! 🔥

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 ![upload_8387b941202216632241764bb15a1d56](https://collective.flashbots.net/uploads/default/original/2X/2/274bd9792474694c0b32c229915a7ae3e184a4ab.png)