Babylon’s BLS Vote Bug Threatens Consensus Stability

Crypto News Exploits

Written by Aaron S.,

Editor-In-Chief

Last Updated: January 09, 2026

Key Takeaways

A flaw in Babylon’s BLS vote extension lets validators skip the block hash, which risks confusion during consensus checks;
Missing block hash data can cause validator crashes and temporary slowdowns at epoch boundaries;
The bug, found by contributor GrumpyLaurie55348, has not been exploited but could disrupt block production if unpatched.

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Babylon’s BLS Vote Bug Threatens Consensus Stability

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Developers of the Babylon staking protocol have revealed a recently discovered software issue that could allow dishonest validators to disrupt the system’s consensus process.

This interference might cause temporary delays in block creation during certain periods.

The problem lies in Babylon’s block verification feature, known as the BLS vote extension. This component ensures that validators agree on which block to add next.

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According to a GitHub post shared on January 8, the issue allows validators to skip an important detail when casting their vote: the block hash.

That missing block hash tells others which block is being approved. Without it, validators can become unsynchronized, especially at epoch boundaries, when special checks occur.

If several validators are affected, this could slow down the overall process of adding new blocks.

The flaw was identified by contributor GrumpyLaurie55348, who explained the effect in their GitHub report.

GrumpyLaurie55348 wrote:

Intermittent validator crashes at epoch boundaries, which would slow down the creation of the epoch boundary block.

They added, "Babylon then dereferences this nil pointer in consensus-critical code paths (notably VerifyVoteExtension, and also proposal-time vote verification), causing a runtime panic".

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