{"id":"CVE-2026-52735","title":"ZEBRA is a Zcash node written entirely in Rust","summary":"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 opcod…","severity":"critical","cwe":["CWE-684"],"vendor":"zebra-script","product":"zebra-script","affected":["zebra-script <= 6.0.1","zebrad <= 4.4.1"],"patched":["zebra-script 7.0.0","zebrad 4.5.0"],"published":"2026-08-18","updated":"2026-09-09","sourceUpdated":"2026-09-09T21:13:25.910","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-52735","references":[{"url":"https://github.com/ZcashFoundation/zebra/commit/1440b43ca7df59aca948090d45117557b217a6cd","label":"security-advisories@github.com"},{"url":"https://github.com/ZcashFoundation/zebra/releases/tag/v4.5.0","label":"security-advisories@github.com"},{"url":"https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-gf9r-m956-97qx","label":"security-advisories@github.com"},{"url":"https://github.com/AlfredoG87/zcash_script/blob/v0.4.4/src/script/iter.rs#L104-L115"},{"url":"https://github.com/ZcashFoundation/zebra/blob/d4cd662c716382f6397d2a730148025a1ca79fec/zebra-consensus/src/block.rs#L140"},{"url":"https://github.com/ZcashFoundation/zebra/blob/d4cd662c716382f6397d2a730148025a1ca79fec/zebra-script/src/lib.rs#L383-L400"},{"url":"https://github.com/advisories/GHSA-gf9r-m956-97qx"}],"tags":["nvd","ghsa","rust"],"epss":0.00291,"epssPercentile":0.21977,"ecosystem":"rust","ingestedAt":"2026-07-02T20:42:45.868Z","slug":"CVE-2026-52735","body":"## Overview\n\nZEBRA 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Package advisory (CVE-2026-52735)\n\nAffected packages:\n\n- `zebra-script <= 6.0.1`\n- `zebrad <= 4.4.1`\n\nPatched in:\n\n- `zebra-script 7.0.0`\n- `zebrad 4.5.0`\n\nSource: https://github.com/advisories/GHSA-gf9r-m956-97qx","depth":"midnight","depthScore":52,"depthScoreParts":{"impact":52.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}