CVE-2026-54496: Zcash HALO2 Gadgets

Critical severity, CVSS 9.3. EPSS: 0.3% chance of exploitation in the next 30 days.

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 (fixed in 0.5.0)
• Zcash Librustzcash: before 0.28.0 (fixed in 0.28.0)
• Zcash Orchard: before 0.14.0 (fixed in 0.14.0)
• Zcash Zcash: before 6.20.0 (fixed in 6.20.0)
• Zcashfoundation Zebra: before 5.0.0 (fixed in 5.0.0)

Published 2026-07-17. Last modified 2026-07-17.