Improper Handling of Highly Compressed Data (Data Amplification) Affecting rabbitmq-server package, versions <3.6.10-1ubuntu0.5+esm1


Severity

Recommended
medium

Based on Ubuntu security rating.

Threat Intelligence

EPSS
0.4% (33rd percentile)

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  • Snyk IDSNYK-UBUNTU1804-RABBITMQSERVER-20126418
  • published18 Oct 2026
  • disclosed23 Sept 2026

Introduced: 23 Sep 2026

CVE-2026-67232  (opens in a new tab)
CWE-409  (opens in a new tab)

How to fix?

Upgrade Ubuntu:18.04 rabbitmq-server to version 3.6.10-1ubuntu0.5+esm1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream rabbitmq-server package and not the rabbitmq-server package as distributed by Ubuntu. See How to fix? for Ubuntu:18.04 relevant fixed versions and status.

RabbitMQ is a messaging and streaming broker. Prior to versions 3.13.15, 4.0.20, 4.1.11, 4.2.6, and 4.3.0, The cowboy WebSocket options at line 117 set compress => true, enabling RFC 7692 permessage-deflate negotiation. The handler 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 the compressed payload with no output-size limit. An attacker can negotiate permessage-deflate during the WebSocket upgrade and send a frame containing a zlib bomb (e.g. 50 KB → 5 GB). Decompression occurs in the connection process before websocket_handle/2 ever sees the MQTT bytes. An unauthenticated attacker can crash a RabbitMQ node running the Web-MQTT plugin by sending a single highly-compressed WebSocket frame (a few KB on the wire) that inflates to gigabytes in memory. The cowboy WebSocket handler decompresses the entire frame before the MQTT CONNECT packet is processed, so no credentials are required. Preconditions include rabbitmq_web_mqtt plugin enabled (not default, but common for browser clients) Network reachability to port 15675/15676 No authentication required. This issue is fixed in versions 3.13.15, 4.0.20, 4.1.11, 4.2.6, and 4.3.0.

CVSS Base Scores

version 3.1