{"id":"CVE-2026-52735","summary":"ZEBRA: Consensus divergence via P2SH sigop undercount in pure-Rust disabled-opcode parser","details":"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.","aliases":["GHSA-gf9r-m956-97qx"],"modified":"2026-08-20T03:54:30.344401402Z","published":"2026-08-18T19:23:10.705Z","database_specific":{"cwe_ids":["CWE-684"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/52xxx/CVE-2026-52735.json","cna_assigner":"GitHub_M"},"references":[{"type":"WEB","url":"https://github.com/ZcashFoundation/zebra/releases/tag/v4.5.0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/52xxx/CVE-2026-52735.json"},{"type":"ADVISORY","url":"https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-gf9r-m956-97qx"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-52735"},{"type":"FIX","url":"https://github.com/ZcashFoundation/zebra/commit/1440b43ca7df59aca948090d45117557b217a6cd"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/zcashfoundation/zebra","events":[{"introduced":"0"},{"fixed":"1440b43ca7df59aca948090d45117557b217a6cd"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"4.5.0"}],"source":["AFFECTED_FIELD","REFERENCES"]}}],"versions":["v4.4.0","v4.4.1","v4.3.1","4.3.1","v4.3.0","v4.2.0","v4.1.0","v4.0.0","v3.1.0","v3.0.0","v3.0.0-rc.0","v2.5.0","v2.0.1","v2.4.2","v2.3.0","v2.4.0","v2.0.0","v2.2.0","v2.1.0","v2.0.0-rc.0","v1.9.0","v1.8.0","v1.7.0","v1.6.1","v1.6.0","v1.5.2","v1.5.1","v1.5.0","v1.4.0","v1.3.0","v1.2.0","v1.1.0","v1.0.1","v1.0.0","v1.0.0-rc.9","v1.0.0-rc.8","v1.0.0-rc.7","v1.0.0-rc.6","v1.0.0-rc.5","v1.0.0-rc.0","v1.0.0-rc.4","v1.0.0-rc.3","v1.0.0-rc.2","v1.0.0-rc.1","v1.0.0-beta.15","v1.0.0-beta.14","v1.0.0-beta.13","v1.0.0-beta.12","v1.0.0-beta.11","v1.0.0-beta.10","v1.0.0-beta.9","v1.0.0-beta.8","v1.0.0-beta.7","v1.0.0-beta.6","v1.0.0-beta.5","v1.0.0-beta.4","v1.0.0-beta.3","v1.0.0-beta.2","v1.0.0-beta.1","v1.0.0-beta.0","v1.0.0-alpha.19","v1.0.0-alpha.18","v1.0.0-alpha.17","v1.0.0-alpha.16","v1.0.0-alpha.15","v1.0.0-alpha.14","v1.0.0-alpha.13","v1.0.0-alpha.12","v1.0.0-alpha.11","v1.0.0-alpha.10","v1.0.0-alpha.9","v1.0.0-alpha.8","v1.0.0-alpha.7","v1.0.0-alpha.6","v1.0.0-alpha.5","v1.0.0-alpha.4","v1.0.0-alpha.3","v1.0.0-alpha.2","v1.0.0-alpha.1","v1.0.0-alpha.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-52735.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"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"}]}