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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-54496
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-17 17:17:16 UTC
Updated2026-07-17 18:45:20 UTC
DescriptionZEBRA 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.

Risk And Classification

Primary CVSS: v3.1 9.3 CRITICAL from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L

EPSS: 0.003150000 probability, percentile 0.236860000 (date 2026-07-20)

Problem Types: CWE-345 | CWE-345 CWE-345: Insufficient Verification of Data Authenticity

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary9.3CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L
3.1CNADECLARED9.3CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
None
Integrity
High
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA ZcashFoundation Zebra affected < 5.0.0 Not specified
CNA Zcash Halo2 Gadgets affected < 0.5.0 Not specified
CNA Zcash Orchard affected < 0.14.0 Not specified
CNA Zcash Librustzcash affected < 0.28.0 Not specified
CNA Zcash Zcash affected < 6.20.0 Not specified

References

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