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CSWSH on Web-STOMP / Web-MQTT (no Origin validation)

Moderate
ansd published GHSA-9c4f-rxxm-88q3 Jul 9, 2026

Software

rabbitmq-server

Affected versions

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

Patched versions

3.13.15
4.0.20
4.1.11
4.2.6

Description

Origin

This vulnerability was identified by Team RabbitMQ and/or other teams at Broadcom, not via a responsible disclosure from an external researcher.

Description

Neither the Web-MQTT handler (deps/rabbitmq_web_mqtt/src/rabbit_web_mqtt_handler.erl:104) nor the Web-STOMP handler (deps/rabbitmq_web_stomp/src/rabbit_web_stomp_handler.erl:102) validates the Origin header on the WebSocket upgrade. Under ssl_cert_login=true, the browser presents the client certificate automatically, so an attacker's JavaScript running in the victim's browser can authenticate as the victim.

Preconditions

The non-default configuration use_http_auth=true (Web-STOMP) or ssl_cert_login=true (both plugins) must be enabled. The issue is harmless under the default in-band CONNECT credential configuration.

CVSS

CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N (5.3, Moderate). Fixed in 3.13.15, 4.0.20, 4.1.11, 4.2.6, 4.3.0.

Severity

Moderate

CVE ID

No known CVE

Weaknesses

Missing Origin Validation in WebSockets

The product uses a WebSocket, but it does not properly verify that the source of data or communication is valid. Learn more on MITRE.