Apache Juneau up to 9.2.0 MessagePack parser allocation of resources

Summaryinfo

A vulnerability, which was classified as problematic, has been found in Apache Juneau up to 9.2.0. This affects an unknown part of the component MessagePack parser. The manipulation leads to allocation of resources. This vulnerability is documented as CVE-2026-73095. The attack can be initiated remotely. There is not any exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in Apache Juneau up to 9.2.0 and classified as problematic. This issue affects an unknown functionality of the component MessagePack parser. The manipulation with an unknown input leads to a allocation of resources vulnerability. Using CWE to declare the problem leads to CWE-770. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor. Impacted is availability. The summary by CVE is:

Allocation of Resources Without Limits or Throttling vulnerability in Apache Juneau. The MessagePack parser, which the REST server enables by default, sizes buffers from length values in the input. An unauthenticated client can send a few bytes that force a multi-gigabyte allocation and an OutOfMemoryError, causing denial of service. Related unbounded allocations in REST request handling (multipart uploads and request reader buffers) are fixed at the same time. This issue affects Apache Juneau: through 9.2.0. Users are recommended to upgrade to version 9.2.1, which fixes the issue.

It is possible to read the advisory at lists.apache.org. The identification of this vulnerability is CVE-2026-73095 since 08/10/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 11/05/2026). The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

Upgrading to version 9.2.1 eliminates this vulnerability.

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Productinfo

Vendor

• Apache

Name

• Juneau

Version

• 9.0
• 9.1
• 9.2.0

License

• open-source

Website

• Vendor: https://www.apache.org/

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