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Zebra has rk Identity Point Panic in Transaction Verification

Critical severity GitHub Reviewed Published Apr 17, 2026 in ZcashFoundation/zebra • Updated Apr 18, 2026

Package

cargo zebra-chain (Rust)

Affected versions

< 6.0.2

Patched versions

6.0.2
cargo zebrad (Rust)
< 4.3.1
4.3.1

Description

rk Identity Point Panic in Transaction Verification

Summary

Orchard transactions contain a rk field which is a randomized validating key and also an elliptic curve point. The Zcash specification allows the field to be the identity (a "zero" value), however, the orchard crate which is used to verify Orchard proofs would panic when fed a rk with the identity value. Thus an attacker could send a crafted transaction that would make a Zebra node crash.

Severity

Critical - This is a Denial of Service Vulnerability that could allow an attacker to crash Zebra nodes.

Affected Versions

All Zebra versions prior to version 4.3.1.

Description

The vulnerability exists in the circuits.rs file of the orchard crate; it attempts to get the coordinates of the rk value and calls unwrap() on the results, which causes a panic if rk is the identity.

Zebra parses rk as a byte vector; it creates an Orchard "bundle" using the orchard crate and then calls the same crate to verify it, triggering the panic.

An attacker could exploit this by:

  1. Creating a transaction with a identity rk
  2. Submitting it to a Zebra node, making it crash

Impact

Denial of Service

  • Attack Vector: Network.
  • Effect: Node crash.
  • Scope: Any impacted Zebra node.

Fixed Versions

This issue is fixed in Zebra 4.3.1.

The fix was agreed with zcashd developers (which has the same issue) to not allow the identity rk anymore and change the specification as such. Zebra now does this when parsing a transaction. This was deemed easier than fixing the issue in orchard, which would make the bug public before the nodes could be patched.

Mitigation

Users should upgrade to Zebra 4.3.1 or later immediately.

There are no known workarounds for this issue. Immediate upgrade is the only way to ensure the node remains not vulnerable to denial of service.

Credits

Thanks to Alex “Scalar” Sol for finding and reporting the issue.

References

@mpguerra mpguerra published to ZcashFoundation/zebra Apr 17, 2026
Published to the GitHub Advisory Database Apr 18, 2026
Reviewed Apr 18, 2026
Last updated Apr 18, 2026

Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity Low
Attack Requirements None
Privileges Required None
User interaction None
Vulnerable System Impact Metrics
Confidentiality None
Integrity None
Availability High
Subsequent System Impact Metrics
Confidentiality None
Integrity None
Availability High

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H

EPSS score

Weaknesses

Reachable Assertion

The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary. Learn more on MITRE.

CVE ID

No known CVE

GHSA ID

GHSA-452v-w3gx-72wg

Source code

Credits

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