Live Exposure Defense: From CVE to Confirmed Exposure in 12 Hours – See more

Back
New CVE Detected

CVE-2026-67232 – Unauthenticated DoS via WebSocket Decompression Bomb – RabbitMQ Web-MQTT Plugin (Co

Be the first to know when new zero-days emerge:

Subscribe to Email Alerts
Subscribe to RSS Feed

Summary

CVE-2026-67232 is a Denial-of-Service vulnerability affecting RabbitMQ’s Web-MQTT plugin, which is built on the Cowboy web server and Cowlib WebSocket library. An unauthenticated attacker can crash a RabbitMQ node by sending a single small, highly-compressed WebSocket frame that decompresses to gigabytes in memory before any MQTT authentication takes place. The issue carries a CVSS score of 8.2 (High).

Technical details

  • Root cause: The Web-MQTT handler enables RFC 7692 permessage-deflate compression (compress => true) on its Cowboy WebSocket listener but does not set max_frame_size, so Cowboy’s default of infinity applies.
  • Cowlib’s cow_ws:parse_payload/9 calls zlib:inflate/2 on incoming compressed WebSocket payloads with no limit on output size.
  • Trigger conditions: The attacker negotiates permessage-deflate during the WebSocket upgrade handshake, then sends a single crafted compressed frame (e.g., ~50 KB) engineered to inflate to several gigabytes (e.g., ~5 GB) during decompression.
  • Attack vector: Decompression happens in the connection process itself, before the MQTT CONNECT packet or any application-layer data is ever inspected — meaning no credentials or prior authentication are required to trigger it.
  • Impact: Memory exhaustion causes the RabbitMQ node’s connection process (and potentially the broader node) to crash, resulting in denial of service for the messaging broker.
  • Preconditions: The rabbitmq_web_mqtt plugin must be enabled (not on by default, but commonly used to support browser-based MQTT clients), and the attacker needs network reachability to the plugin’s listener ports (typically 15675/15676).

Affected software

  • RabbitMQ Server >= 3.13.0, < 3.13.15
  • RabbitMQ Server >= 4.0.0, < 4.0.20
  • RabbitMQ Server >= 4.1.0, < 4.1.11
  • RabbitMQ Server >= 4.2.0, < 4.2.6

Severity

CVSS v4.0 Base Score: 8.2 (High)
Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Mitigation and recommended actions

  • Immediate: Upgrade RabbitMQ Server to one of the fixed releases: 3.13.15, 4.0.20, 4.1.11, 4.2.6, or 4.3.0 (or later).
  • If patching is not immediately possible: Disable the rabbitmq_web_mqtt plugin if it is not required, or restrict network access to its listener ports (default 15675/15676) to trusted clients only via firewall rules or network segmentation.

References

Are you exposed?

Get a free report of your organization’s exposure to this CVE and threat

  • Mapping of all Assets with this Technology
  • Identification of potentially exposed assets to this CVE
  • Confirmation of verified exploitable assets
Get Exposure Report

How IONIX’s External Exposure Management Platform Detects and Validates
Zero-Days to Shrink MTTR

1

Map your entire attack surface (continously)

IONIX uses multi-factor discovery methods, including DNS analysis, certificate mapping, metadata inspection, and more, to automatically map every internet-facing asset across your environment. This includes cloud instances, third-party platforms, shadow IT, and even forgotten infrastructure that traditional tools miss.

2

Monitor for new CVEs

Dozens of threat intel feeds using agentic technology are continuously analyzed to detect the appearance of proof-of-concept code, exploit kits, and indicators of active targeting. IONIX goes further by applying AI to proactively evaluate whether emerging vulnerabilities are likely to be exploited, even before PoCs go public.

3

Identify Potential External Exposures

Not all CVEs matter. IONIX filters vulnerabilities by asking attacker-centric questions: Can it be reached from the internet? Does it require authentication? Is it being exploited in the wild? This dramatically reduces noise and focuses teams on threats that can actually be weaponized.

4

Create Safe, Scalable Exploit Validations

IONIX transforms real-world PoCs into safe, non-intrusive test payloads that can be run in production environments without disruption. These simulations are precisely targeted to the systems that are vulnerable, ensuring rapid validation without unnecessary load.

5

Execute Exploit Validations

By combining context about software stack, versioning, exposure status, and reachability, IONIX ensures that only the right payloads are executed against the right assets, maximizing efficiency and minimizing risk.

6

Drive Fast and Actionable Remediation

Results are routed through integrations with ticketing, SOAR, and SIEM tools. Issues are written in plain language, bundled into remediation clusters, and prioritized based on asset criticality, exploitability, and blast radius. This shortens mean time to remediation (MTTR) and empowers teams to act with confidence.

Are you exposed?

Get a free report of your organization’s exposure to this CVE and threat

  • Mapping of all Assets with this Technology
  • Identification of potentially exposed assets to this CVE
  • Confirmation of verified exploitable assets
Get Exposure Report
Close

Subscribe to Threat Center RSS

Copy/paste the link below into your preferred RSS reader or follow these instructions to subscribe to Slack alerts.

Open RSS feedSlack setup instructions

Close

Get Real-Time CVE Alerts to Your Email

Be the first to know when new zero-days emerge