CVE-2026-33217: CWE-863: Incorrect Authorization in nats-io nats-server
NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versions 2.11.15 and 2.12.6, when using ACLs on message subjects, these ACLs were not applied in the `$MQTT.>` namespace, allowing MQTT clients to bypass ACL checks for MQTT subjects. Versions 2.11.15 and 2.12.6 contain a fix. No known workarounds are available.
AI Analysis
Technical Summary
NATS-Server versions before 2.11.15 and 2.12.6 contain an authorization bypass vulnerability (CWE-863) due to ACLs not being applied to the $MQTT.> namespace. This allows MQTT clients to circumvent ACL restrictions on MQTT subjects, potentially leading to unauthorized actions. The issue is addressed by applying fixes in versions 2.11.15 and 2.12.6. The vulnerability has a CVSS 3.1 base score of 7.1, indicating high severity with low attack complexity, requiring low privileges, no user interaction, and impacts confidentiality and integrity.
Potential Impact
The vulnerability permits MQTT clients to bypass ACL enforcement on MQTT subjects, which can lead to unauthorized access or modification of messages within the NATS messaging system. This impacts the confidentiality and integrity of the messaging data. There are no known exploits in the wild at this time.
Mitigation Recommendations
A fix is available in nats-server versions 2.11.15 and 2.12.6. Users should upgrade to at least these versions to remediate the vulnerability. No workarounds are known. Since this is not a cloud service, remediation must be applied by updating the affected software.
CVE-2026-33217: CWE-863: Incorrect Authorization in nats-io nats-server
Description
NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versions 2.11.15 and 2.12.6, when using ACLs on message subjects, these ACLs were not applied in the `$MQTT.>` namespace, allowing MQTT clients to bypass ACL checks for MQTT subjects. Versions 2.11.15 and 2.12.6 contain a fix. No known workarounds are available.
CVSS v3.1
Score 7.1high
Affected software
pkg:github/nats-io/nats-serverRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
NATS-Server versions before 2.11.15 and 2.12.6 contain an authorization bypass vulnerability (CWE-863) due to ACLs not being applied to the $MQTT.> namespace. This allows MQTT clients to circumvent ACL restrictions on MQTT subjects, potentially leading to unauthorized actions. The issue is addressed by applying fixes in versions 2.11.15 and 2.12.6. The vulnerability has a CVSS 3.1 base score of 7.1, indicating high severity with low attack complexity, requiring low privileges, no user interaction, and impacts confidentiality and integrity.
Potential Impact
The vulnerability permits MQTT clients to bypass ACL enforcement on MQTT subjects, which can lead to unauthorized access or modification of messages within the NATS messaging system. This impacts the confidentiality and integrity of the messaging data. There are no known exploits in the wild at this time.
Mitigation Recommendations
A fix is available in nats-server versions 2.11.15 and 2.12.6. Users should upgrade to at least these versions to remediate the vulnerability. No workarounds are known. Since this is not a cloud service, remediation must be applied by updating the affected software.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-03-17T23:23:58.314Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Vendor Advisory Urls
- [{"url":"https://access.redhat.com/security/cve/CVE-2026-33217","vendor":"Red Hat"},{"url":"https://access.redhat.com/errata/RHSA-2026:22347","vendor":"Red Hat"},{"url":"https://access.redhat.com/errata/RHSA-2026:21769","vendor":"Red Hat"},{"url":"https://access.redhat.com/errata/RHSA-2026:23345","vendor":"Red Hat"}]
Threat ID: 69c43f15f4197a8e3b7dafe0
Added to database: 03/25/2026, 20:01:25 UTC
Last enriched: 07/30/2026, 01:39:22 UTC
Last updated: 07/31/2026, 19:30:22 UTC
Views: 139
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