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, a high-performance messaging server, had a flaw in its ACL enforcement for message subjects within the $MQTT.> namespace. Prior to versions 2.11.15 and 2.12.6, ACLs configured for message subjects were not applied correctly in this namespace, allowing MQTT clients to bypass these controls. This vulnerability could lead to unauthorized access to sensitive message subjects or unauthorized message manipulation. The vulnerability is tracked as CWE-863 (Incorrect Authorization) and CWE-425 (Direct Request 'Forced Browsing'). The issue is fixed in versions 2.11.15 and 2.12.6.
Potential Impact
The vulnerability allows MQTT clients to bypass ACL checks, potentially leading to unauthorized disclosure of information or unauthorized modification of messages within the NATS messaging system. This can compromise confidentiality and integrity of the messaging data. There is no known impact on availability. The CVSS v3.1 score is 7.1 (High), reflecting network attack vector, low attack complexity, low privileges required, no user interaction, and high confidentiality and integrity impacts.
Mitigation Recommendations
A fix is available in nats-server versions 2.11.15 and 2.12.6. Users should upgrade to these or later versions to remediate the vulnerability. No known workarounds or mitigations are available that meet Red Hat's criteria for ease of use and applicability. Therefore, upgrading is the recommended and effective mitigation.
CVE-2026-33217: CWE-863: Incorrect Authorization in nats-io nats-server
Description
NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versions 2.11.15 and 2.12.6, when using ACLs on message subjects, these ACLs were not applied in the `$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
nats-io
nats-server
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, a high-performance messaging server, had a flaw in its ACL enforcement for message subjects within the $MQTT.> namespace. Prior to versions 2.11.15 and 2.12.6, ACLs configured for message subjects were not applied correctly in this namespace, allowing MQTT clients to bypass these controls. This vulnerability could lead to unauthorized access to sensitive message subjects or unauthorized message manipulation. The vulnerability is tracked as CWE-863 (Incorrect Authorization) and CWE-425 (Direct Request 'Forced Browsing'). The issue is fixed in versions 2.11.15 and 2.12.6.
Potential Impact
The vulnerability allows MQTT clients to bypass ACL checks, potentially leading to unauthorized disclosure of information or unauthorized modification of messages within the NATS messaging system. This can compromise confidentiality and integrity of the messaging data. There is no known impact on availability. The CVSS v3.1 score is 7.1 (High), reflecting network attack vector, low attack complexity, low privileges required, no user interaction, and high confidentiality and integrity impacts.
Mitigation Recommendations
A fix is available in nats-server versions 2.11.15 and 2.12.6. Users should upgrade to these or later versions to remediate the vulnerability. No known workarounds or mitigations are available that meet Red Hat's criteria for ease of use and applicability. Therefore, upgrading is the recommended and effective mitigation.
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: 08/13/2026, 16:33:04 UTC
Last updated: 09/13/2026, 22:12:45 UTC
Views: 159
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.