{"id":"EUVD-2026-61166","enisaUuid":"0cebd701-399c-38ad-ae2e-311e34aa4df3","description":"ZEBRA is a Zcash node written entirely in Rust. Prior to 4.5.0, Zebra can accept a block that zcashd rejects because the P2SH signature-operation counter undercounts redeem scripts containing a disabled opcode followed by signature opcodes. In zebra-script/src/lib.rs, p2sh_input_sigop_count used the pure-Rust script::Code::sig_op_count path, whose try_fold parser stops at disabled opcodes such as OP_CODESEPARATOR and returns only the partial count accumulated before the error. The zcashd reference implementation continues static signature-operation counting through disabled opcodes, so an attacker can broadcast P2SH spends that Zebra counts below MAX_BLOCK_SIGOPS while zcashd counts above the 20,000-operation limit. If a Zebra miner includes those transactions, Zebra validators accept the block while zcashd validators reject it, creating a consensus chain split that affects network integrity and availability without requiring the attacker to produce a block. This issue is fixed in version 4.5.0.","datePublished":"Aug 18, 2026, 7:23:10 PM","dateUpdated":"Aug 18, 2026, 7:48:45 PM","baseScore":9.3,"baseScoreVersion":"4.0","baseScoreVector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:H","references":"https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-gf9r-m956-97qx\nhttps://github.com/ZcashFoundation/zebra/commit/1440b43ca7df59aca948090d45117557b217a6cd\nhttps://github.com/ZcashFoundation/zebra/releases/tag/v4.5.0\n","aliases":"CVE-2026-52735\nGHSA-gf9r-m956-97qx\n","assigner":"GitHub_M","epss":0.51,"enisaIdProduct":[{"id":"7b32a509-bdc6-3459-a09c-4b5c4251532c","product":{"name":"zebra","vendor":{"name":"ZcashFoundation"}},"product_version":"\u003c 4.5.0"}],"enisaIdVendor":[{"id":"557e2a46-dca8-358d-baa0-43a9c437936a","vendor":{"name":"ZcashFoundation"}}],"enisaIdVulnerability":[{"id":"7664d870-b13e-3c93-ac61-90754fac4e02","vulnerability":{"id":"CVE-2026-52735","description":"ZEBRA is a Zcash node written entirely in Rust. Prior to 4.5.0, Zebra can accept a block that zcashd rejects because the P2SH signature-operation counter undercounts redeem scripts containing a disabled opcode followed by signature opcodes. In zebra-script/src/lib.rs, p2sh_input_sigop_count used the pure-Rust script::Code::sig_op_count path, whose try_fold parser stops at disabled opcodes such as OP_CODESEPARATOR and returns only the partial count accumulated before the error. The zcashd reference implementation continues static signature-operation counting through disabled opcodes, so an attacker can broadcast P2SH spends that Zebra counts below MAX_BLOCK_SIGOPS while zcashd counts above the 20,000-operation limit. If a Zebra miner includes those transactions, Zebra validators accept the block while zcashd validators reject it, creating a consensus chain split that affects network integrity and availability without requiring the attacker to produce a block. This issue is fixed in version 4.5.0.","datePublished":"Aug 18, 2026, 7:23:10 PM","dateUpdated":"Aug 18, 2026, 7:48:45 PM","status":"PUBLISHED","baseScore":9.3,"baseScoreVersion":"4.0","baseScoreVector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:H","references":"https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-gf9r-m956-97qx\nhttps://github.com/ZcashFoundation/zebra/commit/1440b43ca7df59aca948090d45117557b217a6cd\nhttps://github.com/ZcashFoundation/zebra/releases/tag/v4.5.0\n","enisa_id":"EUVD-2026-61166\n","assigner":"GitHub_M","epss":0.51,"dataProcessed":"Oct 28, 2026, 7:15:32 AM","vulnerabilityProduct":[{"id":"f31a6d56-d73b-3cf9-9a1a-b1e067fbdb30","product":{"name":"zebra","vendor":{"name":"ZcashFoundation"}},"product_version":"\u003c 4.5.0"}],"vulnerabilityVendor":[{"id":"cf334882-2368-3486-bbb4-75e0e2a79181","vendor":{"name":"ZcashFoundation"}}]}},{"id":"cef66572-c0ea-3269-86db-703b86f6e0f6","vulnerability":{"id":"GHSA-gf9r-m956-97qx","description":"zebrad has consensus divergence via P2SH sigop undercount in pure-Rust disabled-opcode parser","datePublished":"Jul 2, 2026, 7:43:36 PM","dateUpdated":"Jul 2, 2026, 7:43:36 PM","baseScore":0.0,"references":"https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-gf9r-m956-97qx\nhttps://github.com/AlfredoG87/zcash_script/blob/v0.4.4/src/script/iter.rs#L104-L115\nhttps://github.com/ZcashFoundation/zebra\nhttps://github.com/ZcashFoundation/zebra/blob/d4cd662c716382f6397d2a730148025a1ca79fec/zebra-consensus/src/block.rs#L140\nhttps://github.com/ZcashFoundation/zebra/blob/d4cd662c716382f6397d2a730148025a1ca79fec/zebra-script/src/lib.rs#L383-L400\n","enisa_id":"EUVD-2026-61166\n","aliases":"CVE-2026-52735\nGHSA-gf9r-m956-97qx\n","epss":0.0,"dataProcessed":"Oct 25, 2026, 1:57:47 AM","vulnerabilityProduct":[],"vulnerabilityVendor":[]}}],"enisaIdAdvisory":[]}