{"id":"CVE-2026-52735","revision":"7e64c357b1d848f5838e6fda090bd408","records":[{"revision":"7e64c357b1d848f5838e6fda090bd408","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-52735","aliases":[],"title":"ZEBRA: Consensus divergence via P2SH sigop undercount in pure-Rust disabled-opcode parser","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.","state":0,"publishedAt":"2026-08-18T19:23:10.705+00:00","modifiedAt":"2026-08-18T19:48:45.15+00:00","affected":[{"ecosystem":"Vendor product","name":"zebra","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"ZcashFoundation\",\n                    \"product\": \"zebra\",\n                    \"versions\": [\n                        {\n                            \"version\": \"< 4.5.0\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 4.0","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,"severity":"CRITICAL"}],"references":["https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-gf9r-m956-97qx","https://github.com/ZcashFoundation/zebra/commit/1440b43ca7df59aca948090d45117557b217a6cd","https://github.com/ZcashFoundation/zebra/releases/tag/v4.5.0"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-52735","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-52735","identifiers":["CVE-2026-52735"]},"retained":false,"historicalAffected":[]}],"coverage":[]}