What’s Vulnerable › Vulnerabilities

CVE-2026-54496: Missing copy constraint in halo2_gadgets variable-base scalar multiplication allows under-constrained base, breaking Orchard Action circuit soundness

• Severity: critical (CVSS 9.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-17 · updated 2026-07-17
• Weakness: CWE-345

Description

ZEBRA is a Zcash node written entirely in Rust. Prior to zebrad 5.0.0, halo2_gadgets 0.5.0, orchard 0.14.0, zcash_primitives 0.28.0, and zcashd 6.20.0, the variable-base scalar multiplication gadget in halo2_gadgets/src/ecc/chip/mul/incomplete.rs used assign_advice() for the base point without a copy constraint tying it to the actual base, allowing a malicious prover to produce a valid proof for an Orchard Action with an under-constrained base point and bypass the diversified-address-integrity check that binds pk_d, g_d, ivk, the nullifier (nf), and the spend validating key (ak) to the note being spent. This issue is fixed in zebrad 5.0.0, halo2_gadgets 0.5.0, orchard 0.14.0, zcash_primitives 0.28.0, and zcashd 6.20.0.

Affected products

• zcash halo2_gadgets: before 0.5.0
• zcash librustzcash: before 0.28.0
• zcash orchard: before 0.14.0
• zcash: before 6.20.0
• ZcashFoundation zebra: before 5.0.0

References

• https://github.com/ZcashFoundation/zebra/releases/tag/v5.0.0
• https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-ww9q-8r59-xv46
• https://github.com/zcash/halo2/releases/tag/halo2_gadgets-0.5.0
• https://github.com/zcash/librustzcash/releases/tag/zcash_primitives-0.28.0
• https://github.com/zcash/orchard/releases/tag/0.14.0
• https://github.com/zcash/zcash/releases/tag/v6.20.0
• https://zfnd.org/zebra-4-5-3-and-5-0-0-emergency-soft-fork-and-nu6-2-activation

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