Consensus split via P2SH sigop undercount
Published Aug 18, 2026 · Updated Aug 18, 2026
Consensus divergence in Zebra before 4.5.0 allows attackers to split validation from zcashd via crafted P2SH redeem scripts. In zebra-script/src/lib.rs, p2sh_input_sigop_count calls a pure-Rust sig_op_count path whose parser stops at disabled opcodes and returns only the partial signature-operation count, while zcashd continues counting through those opcodes during static analysis. All default validating deployments are affected, and an attacker only needs a Zebra miner to include the crafted spends to make Zebra accept a block that zcashd rejects.
Summary
What happened
Consensus divergence in Zebra before 4.5.0 allows attackers to split validation from zcashd via crafted P2SH redeem scripts. In zebra-script/src/lib.rs, p2sh_input_sigop_count calls a pure-Rust sig_op_count path whose parser stops at disabled opcodes and returns only the partial signature-operation count, while zcashd continues counting through those opcodes during static analysis. All default validating deployments are affected, and an attacker only needs a Zebra miner to include the crafted spends to make Zebra accept a block that zcashd rejects.
The record
- CVE
- CVE-2026-52735
- Published
- Aug 18, 2026
- Updated
- Aug 18, 2026
- Vendor
- Zcash Foundation
- Product
- Zebra
- Classifications
- CWE-684
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 18, 2026CVE publishedPublication date reported by the CVE source.
- Aug 18, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 4.5.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo