# CVE-2026-66274: Apache Qpid Proton-J: Unbounded type nesting can lead to pre-authentication stackoverflow

Source: https://junglewise.ai/threats/cve-2026-66274-apache-qpid-proton-j-unbounded-type-nesting-can-lead-to-pre  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-05  
License: CC BY 4.0 with a link back

CVE-2026-66274 · Severity: high · CVSS 7.5 · Published 2026-08-05

A pre-authentication attacker could leverage type nesting to cause a StackOverflowError potentially leading to denial of service.

This issue affects Apache Qpid Proton-J: through 0.34.1.

Users are recommended to upgrade to version 0.35.0, which fixes the issue.

Technologies: [org.apache.qpid:proton-j (Maven)](https://junglewise.ai/threats/technologies/org-apache-qpid-proton-j). Vendors: [Maven](https://junglewise.ai/threats/vendors/maven).

## Quick answers

**Is CVE-2026-66274 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-66274 being exploited in the wild.

**How severe is CVE-2026-66274?** High severity, with a CVSS score of 7.5, published 5 August 2026.

**Which products and versions are affected?** org.apache.qpid:proton-j (Maven) < 0.35.0, ECOSYSTEM:introduced=0,fixed=0.35.0.

**Is there a fix for CVE-2026-66274?** Yes. org.apache.qpid:proton-j (Maven): upgrade to 0.35.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**Am I affected by CVE-2026-66274?** Check whether you run org.apache.qpid:proton-j (Maven) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- org.apache.qpid:proton-j (Maven): upgrade to 0.35.0 or later

  ```sh
  # set org.apache.qpid:proton-j to 0.35.0 in your pom.xml or build.gradle
  ```


## Affected products

- org.apache.qpid:proton-j (Maven) < 0.35.0, ECOSYSTEM:introduced=0,fixed=0.35.0

## Identifiers

- CVE-2026-66274
- GHSA-p2gc-fm5w-94jj

## Related threats

- [Withdrawn Advisory: Improper Certificate Validation in Apache Qpid Proton](https://junglewise.ai/threats/cve-2019-0223-withdrawn-advisory-improper-certificate-validation-in-apache-qpid)
- [Improper Certificate Validation in proton-j](https://junglewise.ai/threats/cve-2018-17187-improper-certificate-validation-in-proton-j)
- [Moderate severity vulnerability that affects org.apache.qpid:proton-j](https://junglewise.ai/threats/cve-2016-2166-moderate-severity-vulnerability-that-affects-org-apache-qpid)