{"cve":"CVE-2026-52735","nvd":{"published":"2026-08-18T20:17:17.227","modified":"2026-10-22T22:10:00.250","status":"Deferred","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.","cvss_v4":{"vector":"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","score":9.3},"cvss_v3":null,"cwes":["CWE-684"],"references":["https://github.com/ZcashFoundation/zebra/commit/1440b43ca7df59aca948090d45117557b217a6cd","https://github.com/ZcashFoundation/zebra/releases/tag/v4.5.0","https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-gf9r-m956-97qx"],"products":[],"source":"nvd","synced_at":"2026-10-23T16:39:26.291718493+00:00"},"epss":{"cve":"CVE-2026-52735","score":0.00507,"percentile":0.42958,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-gf9r-m956-97qx","url":"https://osv.dev/vulnerability/GHSA-gf9r-m956-97qx","summary":"zebrad has consensus divergence via P2SH sigop undercount in pure-Rust disabled-opcode parser","modified":"2026-07-02T20:11:29.482145Z","packages":[{"ecosystem":"crates.io","name":"zebra-script","purl":"pkg:cargo/zebra-script","ranges":["<7.0.0"],"fixed":["7.0.0"]},{"ecosystem":"crates.io","name":"zebrad","purl":"pkg:cargo/zebrad","ranges":["<4.5.0"],"fixed":["4.5.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}