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Advisories

Zebra 4.5.0 Consensus Split via P2SH Sigop Overcount

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severity
high
date
Affecting

  • zebra >= 4.5.0, < 4.5.1

  • zebra >= 7.0.0, < 7.0.1

CWE
  • CWE-628 Function Call with Incorrectly Specified Arguments
CVSS
8.7
CVSS V4 Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Credit
sangsoo-osec
Description
Zebra zebrad 4.5.0 and zebra-script 7.0.0 count P2SH redeem script signature operations in legacy mode rather than zcashd's accurate P2SH mode, overcounting CHECKMULTISIG preceded by OP_1 through OP_16 as 20 sigops and causing a consensus divergence. Remote attackers can broadcast P2SH spends using low-threshold multisig redeem scripts so that a block zcashd accepts exceeds Zebra's inflated MAX_BLOCK_SIGOPS count, causing Zebra nodes to reject it and stall off the chain.

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