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Zebra Vulnerable to Denial of Service via Interrupted JSON-RPC Requests from Authenticated Clients

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

Package

cargo zebra-rpc (Rust)

Affected versions

>= 1.0.0-beta.45, < 6.0.2

Patched versions

6.0.2
cargo zebrad (Rust)
>= 2.2.0, < 4.3.1
4.3.1

Description

A vulnerability in Zebra's JSON-RPC HTTP middleware allows an authenticated RPC client to cause a Zebra node to crash by disconnecting before the request body is fully received. The node treats the failure to read the HTTP request body as an unrecoverable error and aborts the process instead of returning an error response.

Severity

Moderate - This is a Denial of Service (DoS) that requires a client capable of passing Zebra's cookie authentication, which is enabled by default.

Affected Versions

  • zebrad: versions from 2.2.0 up to (but not including) 4.3.1
  • zebra-rpc: versions from 1.0.0-beta.45 up to (but not including) 6.0.2

Description

Zebra's JSON-RPC HTTP middleware treated a failure to read the incoming HTTP request body as an unrecoverable error, aborting the process rather than returning an error response. A client that disconnected after sending only part of a request body, for example, by resetting the TCP connection mid-transfer, was sufficient to trigger the crash. The vulnerability could be exploited only by authenticated RPC clients. Nodes running the shipped defaults, with RPC bound to localhost and cookie authentication on, were not vulnerable.

Impact

Denial of Service

  • Attack Vector: Network, authenticated (requires a valid RPC cookie when cookie authentication is enabled).
  • Effect: Immediate crash of the Zebra node.
  • Scope: Any node whose RPC interface is reachable by a client with valid credentials, or any node with cookie authentication disabled and an exposed RPC interface.

Fixed Versions

This issue is fixed in Zebra 4.3.1 (crate zebra-rpc 6.0.2).

The fix propagates failures to read the HTTP request body as ordinary error responses, so Zebra now rejects truncated or interrupted requests rather than crashing.

Mitigation

Users should upgrade to Zebra 4.3.1 or later.

If an immediate upgrade is not possible, users should ensure their RPC port is not exposed to untrusted networks and that cookie authentication remains enabled (the default).

References

Credits

Thanks to shieldedonly who discovered this issue and reported it via our coordinated disclosure process.

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

Moderate

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 Present
Privileges Required High
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:P/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H

EPSS score

Weaknesses

Uncaught Exception

An exception is thrown from a function, but it is not caught. Learn more on MITRE.

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-29x4-r6jv-ff4w

Source code

Credits

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