{"api_version":"1","generated_at":"2026-08-21T20:40:41+00:00","cve":"CVE-2026-52735","urls":{"html":"https://cve.report/CVE-2026-52735","api":"https://cve.report/api/cve/CVE-2026-52735.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-52735","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-52735"},"summary":{"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":"PUBLISHED","assigner":"GitHub_M","published_at":"2026-08-18 20:17:17","updated_at":"2026-08-18 20:17:17"},"problem_types":["CWE-684","CWE-684 CWE-684: Incorrect Provision of Specified Functionality"],"metrics":[{"version":"4.0","source":"security-advisories@github.com","type":"Secondary","score":"9.3","severity":"CRITICAL","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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","data":{"version":"4.0","vectorString":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","baseScore":9.3,"baseSeverity":"CRITICAL","attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"HIGH","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"HIGH","subAvailabilityImpact":"HIGH","exploitMaturity":"NOT_DEFINED","confidentialityRequirement":"NOT_DEFINED","integrityRequirement":"NOT_DEFINED","availabilityRequirement":"NOT_DEFINED","modifiedAttackVector":"NOT_DEFINED","modifiedAttackComplexity":"NOT_DEFINED","modifiedAttackRequirements":"NOT_DEFINED","modifiedPrivilegesRequired":"NOT_DEFINED","modifiedUserInteraction":"NOT_DEFINED","modifiedVulnConfidentialityImpact":"NOT_DEFINED","modifiedVulnIntegrityImpact":"NOT_DEFINED","modifiedVulnAvailabilityImpact":"NOT_DEFINED","modifiedSubConfidentialityImpact":"NOT_DEFINED","modifiedSubIntegrityImpact":"NOT_DEFINED","modifiedSubAvailabilityImpact":"NOT_DEFINED","Safety":"NOT_DEFINED","Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","valueDensity":"NOT_DEFINED","vulnerabilityResponseEffort":"NOT_DEFINED","providerUrgency":"NOT_DEFINED"}},{"version":"4.0","source":"CNA","type":"DECLARED","score":"9.3","severity":"CRITICAL","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","data":{"attackComplexity":"LOW","attackRequirements":"NONE","attackVector":"NETWORK","baseScore":9.3,"baseSeverity":"CRITICAL","privilegesRequired":"NONE","subAvailabilityImpact":"HIGH","subConfidentialityImpact":"NONE","subIntegrityImpact":"HIGH","userInteraction":"NONE","vectorString":"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","version":"4.0","vulnAvailabilityImpact":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"HIGH"}}],"references":[{"url":"https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-gf9r-m956-97qx","name":"https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-gf9r-m956-97qx","refsource":"security-advisories@github.com","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://github.com/ZcashFoundation/zebra/commit/1440b43ca7df59aca948090d45117557b217a6cd","name":"https://github.com/ZcashFoundation/zebra/commit/1440b43ca7df59aca948090d45117557b217a6cd","refsource":"security-advisories@github.com","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://github.com/ZcashFoundation/zebra/releases/tag/v4.5.0","name":"https://github.com/ZcashFoundation/zebra/releases/tag/v4.5.0","refsource":"security-advisories@github.com","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-52735","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-52735","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"ZcashFoundation","product":"zebra","version":"affected < 4.5.0","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"adp":[{"metrics":[{"other":{"content":{"id":"CVE-2026-52735","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","timestamp":"2026-08-18T19:48:36.850142Z","version":"2.0.3"},"type":"ssvc"}}],"providerMetadata":{"dateUpdated":"2026-08-18T19:48:45.150Z","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP"},"title":"CISA ADP Vulnrichment"}],"cna":{"affected":[{"product":"zebra","vendor":"ZcashFoundation","versions":[{"status":"affected","version":"< 4.5.0"}]}],"descriptions":[{"lang":"en","value":"ZEBRA is a Zcash node written entirely in Rust. 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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. 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