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0xCERT Security Advisory 0xCERT-2026-0212
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Advisory-ID:  0xCERT-2026-0212
Severity:     Critical
Published:    2026-07-06T21:23:41.000Z
Updated:      2026-10-08T22:47:35.286Z
Chains:       n/a
URL:          https://www.0xcert.com/advisory/0xCERT-2026-0212

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

Summary
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Zebra: Missing copy constraint in halo2_gadgets variable-base scalar multiplication allows under-constrained base, breaking Orchard Action circuit soundness. A soundness vulnerability in the variable-base scalar multiplication gadget of halo2gadgets allowed a malicious prover to produce a valid proof for an Orchard Action with an under-constrained base point.

Details
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Summary
A soundness vulnerability in the variable-base scalar multiplication gadget of halo2gadgets allowed a malicious prover to produce a valid proof for an Orchard Action with an under-constrained base point.

Affected
- - zebrad (rust) <= 4.5.1 — fixed in 5.0.0
- - halo2_gadgets (rust) < 0.5.0 — fixed in 0.5.0
- - orchard (rust) < 0.14.0 — fixed in 0.14.0
- - zcash_primitives (rust) < 0.28.0 — fixed in 0.28.0

Severity
Critical, as rated by the upstream advisory.

Recommended actions
- - Upgrade zebrad to 5.0.0 or later
- - Upgrade halo2_gadgets to 0.5.0 or later
- - Upgrade orchard to 0.14.0 or later
- - Upgrade zcash_primitives to 0.28.0 or later

Source & attribution
This 0xCERT advisory summarises GHSA-ww9q-8r59-xv46 / CVE-2026-54496 from the GitHub Advisory Database, credited upstream to defuse, nuttycom, daira, conradoplg, mpguerra: https://github.com/advisories/GHSA-ww9q-8r59-xv46. Details may change; refer to the original source for the authoritative record.

References
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- - https://github.com/advisories/GHSA-ww9q-8r59-xv46
- - CVE-2026-54496
- - https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-ww9q-8r59-xv46

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