OpenBao up to 2.4.0 JSON max_request_size resource consumption

Summaryinfo

A vulnerability identified as problematic has been detected in OpenBao up to 2.4.0. The affected element is an unknown function of the component JSON Handler. This manipulation of the argument max_request_size causes resource consumption. The identification of this vulnerability is CVE-2025-59043. It is possible to initiate the attack remotely. There is no exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in OpenBao up to 2.4.0. It has been declared as problematic. Affected by this vulnerability is some unknown functionality of the component JSON Handler. The manipulation of the argument max_request_size with an unknown input leads to a resource consumption vulnerability. The CWE definition for the vulnerability is CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. As an impact it is known to affect availability. The summary by CVE is:

OpenBao is an open source identity-based secrets management system. In OpenBao versions prior to 2.4.1, JSON objects after decoding may use significantly more memory than their serialized version. It is possible to craft a JSON payload to maximize the factor between serialized memory usage and deserialized memory usage, similar to a zip bomb, with factors reaching approximately 35. This can be used to circumvent the max_request_size configuration parameter which is intended to protect against denial of service attacks. The request body is parsed into a map very early in the request handling chain before authentication, which means an unauthenticated attacker can send a specifically crafted JSON object and cause an out-of-memory crash. Additionally, for requests with large numbers of strings, the audit subsystem can consume large quantities of CPU. The vulnerability is fixed in version 2.4.1.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2025-59043 since 09/08/2025. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

Upgrading to version 2.4.1 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2025-34895). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Name

• OpenBao

Version

• 2.0
• 2.1
• 2.2
• 2.3
• 2.4.0

Website

• Product: https://github.com/openbao/openbao/

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Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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