CVE-2026-58214: CWE-863: Incorrect Authorization in nats-io nats-server
NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.3 and 2.12.12, an authenticated MQTT client could subscribe to the internal $MQTT.deliver.pubrel subject family, bypassing configured subscribe permissions and exposing MQTT QoS2 protocol metadata for sessions in the account. This issue is fixed in versions 2.14.3 and 2.12.12.
AI Analysis
Technical Summary
CVE-2026-58214 is an incorrect authorization vulnerability (CWE-863) in nats-io nats-server. Authenticated MQTT clients could bypass subscription permissions to access internal MQTT QoS2 protocol metadata by subscribing to the $MQTT.deliver.pubrel subject family. This exposure affects versions prior to 2.12.12 and versions from 2.12.12 up to but not including 2.14.3. The vulnerability is fixed in versions 2.12.12 and 2.14.3.
Potential Impact
The vulnerability allows an authenticated MQTT client to bypass subscription permissions and access internal MQTT QoS2 protocol metadata for sessions within the account. The impact is limited to confidentiality (partial exposure of protocol metadata) without affecting integrity or availability. The CVSS 3.1 base score is 4.3 (medium severity), reflecting a network attack vector with low complexity and requiring privileges but no user interaction.
Mitigation Recommendations
Upgrade affected nats-server instances to version 2.12.12 or later, or 2.14.3 or later, where this authorization bypass vulnerability is fixed. No other mitigations are indicated. Patch status is confirmed fixed in these versions.
CVE-2026-58214: CWE-863: Incorrect Authorization in nats-io nats-server
Description
NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.3 and 2.12.12, an authenticated MQTT client could subscribe to the internal $MQTT.deliver.pubrel subject family, bypassing configured subscribe permissions and exposing MQTT QoS2 protocol metadata for sessions in the account. This issue is fixed in versions 2.14.3 and 2.12.12.
CVSS v3.1
Score 4.3medium
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.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-58214 is an incorrect authorization vulnerability (CWE-863) in nats-io nats-server. Authenticated MQTT clients could bypass subscription permissions to access internal MQTT QoS2 protocol metadata by subscribing to the $MQTT.deliver.pubrel subject family. This exposure affects versions prior to 2.12.12 and versions from 2.12.12 up to but not including 2.14.3. The vulnerability is fixed in versions 2.12.12 and 2.14.3.
Potential Impact
The vulnerability allows an authenticated MQTT client to bypass subscription permissions and access internal MQTT QoS2 protocol metadata for sessions within the account. The impact is limited to confidentiality (partial exposure of protocol metadata) without affecting integrity or availability. The CVSS 3.1 base score is 4.3 (medium severity), reflecting a network attack vector with low complexity and requiring privileges but no user interaction.
Mitigation Recommendations
Upgrade affected nats-server instances to version 2.12.12 or later, or 2.14.3 or later, where this authorization bypass vulnerability is fixed. No other mitigations are indicated. Patch status is confirmed fixed in these versions.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-06-29T17:09:25.873Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a4eafe7c9d9e3dbe3adea2e
Added to database: 07/08/2026, 20:15:35 UTC
Last enriched: 07/16/2026, 10:12:53 UTC
Last updated: 08/22/2026, 10:52:10 UTC
Views: 82
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