AIKIDO-2026-930318
zebra-script is vulnerable to Incorrect Calculation
93
Critical Risk
This Affects:
zebra-scriptTL;DR
The P2SH signature-operation counter in zebra-script counts an extracted redeem script with the legacy counting mode instead of the accurate P2SH mode. A CHECKMULTISIG preceded by a small OP_N push is over-counted as twenty signature operations rather than its true key count. Blocks whose true block-wide sigop total stays under the consensus limit are then rejected while other implementations accept them, producing a consensus divergence and chain split. The fix restores accurate P2SH sigop counting so the total matches the reference implementation.
Who does this affect?
You are affected if you are using a version that falls within the vulnerable range and your node validates blocks on a network shared with other Zcash consensus implementations.
Background info
zebra-script is vulnerable to Incorrect Calculation in versions 7.0.0 - 7.0.0.
How to fix this
Upgrade the zebra-script library to the patch version.
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