SB2026110336 - Fedora 43 update for rabbitmq-server
Published: November 3, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 4 vulnerabilities.
1) Unchecked Return Value (CVE-ID: CVE-2026-67409)
CWE-ID: CWE-252 - Unchecked Return Value
CVSSv4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to unchecked return value in the JWKS key fetching mechanism in uaa_jwt.erl when processing JWKS endpoint responses during signing key refresh. A remote attacker can send a crafted JWT with an unknown kid value to cause a denial of service.
Exploitation requires RabbitMQ to be configured with OAuth2 authentication using JWKS-based key discovery, and the JWKS endpoint must return an error response with a valid JSON body that lacks a keys field.
2) Input validation error (CVE-ID: CVE-2026-67416)
CWE-ID: CWE-20 - Improper input validation
CVSSv4: 5.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]
The vulnerability allows a remote user to cause a denial of service in consumer sessions or channels.
The vulnerability exists due to improper input validation in the optimized AMQP 1.0 server_mode parser and cross-protocol conversion paths when processing AMQP 1.0 messages with symbolic body descriptors that match a fixed textual prefix but use a different encoded symbol length. A remote user can publish a specially crafted AMQP 1.0 message to cause a denial of service in consumer sessions or channels.
Exploitation requires the ability to authenticate over AMQP 1.0, write to a target exchange or queue, and have the stored message consumed through a strict AMQP 1.0 decoder or a protocol path that forces full AMQP body decoding.
3) Input validation error (CVE-ID: CVE-2026-67418)
CWE-ID: CWE-20 - Improper input validation
CVSSv4: 5.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]
The vulnerability allows a remote user to cause a denial of service.
The vulnerability exists due to improper input validation in the MQTT 5 property parser and outbound PUBLISH property serializer when processing a crafted MQTT 5 PUBLISH packet containing an inapplicable property. A remote user can send a specially crafted PUBLISH message to cause a denial of service.
MQTT or Web MQTT must be enabled, and exploitation requires a separately authenticated MQTT 5 or Web MQTT subscriber on a matching topic or subscription filter.
4) Improper access control (CVE-ID: CVE-2026-67420)
CWE-ID: CWE-284 - Improper Access Control
CVSSv4: 5.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote user to publish messages with a foreign AMQP user_id after that privilege should have been revoked.
The vulnerability exists due to improper access control in rabbit_access_control:update_state/2 and rabbit_access_control:check_user_id/2 when refreshing an existing AMQP connection from an OAuth token that no longer grants the impersonator tag. A remote user can refresh the connection with a same-username token that omits the impersonator tag to publish messages with a foreign AMQP user_id after that privilege should have been revoked.
Only connections that previously held the impersonator tag are affected. The issue requires a refresh-capable OAuth backend for AMQP, a successful credential refresh before the original credential-expiry timer closes the connection, and it affects both existing and newly opened channels on the refreshed connection.
Remediation
Install update from vendor's website.