VulnerabilityPublished 6 Jul 2026

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

Affects zebradSource GCVE Database

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Not known to be exploited · CVSS 9.3 Critical : upgrade to 5.0.0 as a priority.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score

9.3Critical

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.3% chance of exploitation in 30 days – higher than 24% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 5.0.0, 0.5.0, 0.14.0 +1

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

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

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 6 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
crates.iozebrad	Affected <5.0.0	Fixed in 5.0.0
crates.iohalo2_gadgets	Affected <0.5.0	Fixed in 0.5.0
crates.ioorchard	Affected <0.14.0	Fixed in 0.14.0
crates.iozcash_primitives	Affected <0.28.0	Fixed in 0.28.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Until a fix is confirmed, avoid using affected versions and consider upgrading to versions where this vulnerability is addressed. No specific temporary mitigations are indicated in the provided data.

Description

A soundness vulnerability in the variable-base scalar multiplication gadget of halo2_gadgets in the Zebrad product allowed a malicious prover to bypass the diversified-address-integrity check in Orchard Actions. This flaw enabled an adversary to produce valid proofs with an under-constrained base point, effectively allowing double-spends within the Orchard pool or theft of funds by forging spend authorizations. Exploitation is undetectable on-chain and could result in balance violations within the Orchard pool without inflating the overall ZEC supply. The vulnerability existed since the Orchard pool introduction in May 2022 and has been remediated. No evidence of exploitation prior to the fix is known.

Impact

An attacker can bypass the diversified-address-integrity check in Orchard Actions, enabling double-spends within the Orchard pool by producing multiple valid nullifiers for the same note. This results in balance violations within the pool but does not inflate the total ZEC supply due to the turnstile mechanism. Alternatively, an attacker who knows the note plaintext can forge spend authorizations to steal funds, potentially bypassing hardware wallet protections if the software wallet is compromised. Exploitation is undetectable on-chain for double-spends, and theft detection relies on the legitimate holder's inability to spend stolen funds or observing the nullifier on-chain. The vulnerability existed since May 31, 2022, with no known exploitation before remediation.

Summary

The vulnerability arises from a missing copy constraint in the double-and-add implementation of variable-base scalar multiplication in halo2_gadgets (specifically in incomplete.rs). The base point is assigned as a private circuit input without a constraint tying it to the actual base, allowing a malicious prover to choose an arbitrary base for the incomplete-addition loop. This breaks the soundness of the Orchard Action's diversified-address-integrity condition, which normally binds the action to the correct incoming viewing key and nullifier. Consequently, an attacker can produce valid proofs for actions with incorrect nullifiers, enabling double-spends or theft of funds by forging spend authorizations if the note plaintext is known. The flaw affects versions of Zebrad prior to 5.0.0, 0.5.0, 0.14.0, and 0.28.0. The vulnerability is critical due to its impact on transaction integrity and undetectability on-chain.

CWE-345Insufficient Verification of Data Authenticity (opens in a new tab)
Class weaknessOWASP Top 10 A08:2025: Software or Data Integrity Failures (opens in a new tab)
The product does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
OWASP Cheat Sheets
XML Security (opens in a new tab)
REST Security (opens in a new tab)
JSON Web Token for Java (opens in a new tab)
REST Assessment (opens in a new tab)
Cross-Site Request Forgery Prevention (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.2 (opens in a new tab)
V3.5.3 (opens in a new tab)
V13.2.6 (opens in a new tab)
Attack patterns
JSON Hijacking (aka JavaScript Hijacking) (opens in a new tab)
Cache Poisoning (opens in a new tab)
DNS Cache Poisoning (opens in a new tab)
Spoofing of UDDI/ebXML Messages (opens in a new tab)
Application API Message Manipulation via Man-in-the-Middle (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 18 Jul 2026, 11:19 UTC

WeaknessesCWE-345

Technical details

References

Community reviews

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