CVE-2026-58254: 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 2.12.8, message trace destination checks were applied to ordinary client connections but not consistently to messages arriving through leafnode connections, allowing a leafnode operator to send trace events to subjects that would not otherwise be permitted and to use trace-only behavior to prevent normal delivery or storage of affected messages. This issue is fixed in versions 2.14.3 and 2.12.8.
AI Analysis
Technical Summary
NATS Server versions before 2.14.3 and 2.12.8 do not consistently enforce message trace destination authorization checks on messages received via leafnode connections. While ordinary client connections are checked properly, leafnode connections bypass these checks, enabling a leafnode operator to send trace events to subjects that would normally be restricted. This can be exploited to use trace-only behavior to prevent the normal delivery or storage of messages on those subjects. The issue is addressed in versions 2.14.3 and 2.12.8.
Potential Impact
An attacker with leafnode operator privileges can send trace events to unauthorized subjects, potentially interfering with message delivery or storage by leveraging trace-only behavior. This could disrupt normal messaging operations within the affected NATS Server deployments.
Mitigation Recommendations
This vulnerability is fixed in nats-server versions 2.14.3 and 2.12.8. Users should upgrade to at least these versions to remediate the issue. No other mitigation or temporary workaround is indicated in the available data.
CVE-2026-58254: 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 2.12.8, message trace destination checks were applied to ordinary client connections but not consistently to messages arriving through leafnode connections, allowing a leafnode operator to send trace events to subjects that would not otherwise be permitted and to use trace-only behavior to prevent normal delivery or storage of affected messages. This issue is fixed in versions 2.14.3 and 2.12.8.
CVSS v4.0
Score 5.3medium
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
NATS Server versions before 2.14.3 and 2.12.8 do not consistently enforce message trace destination authorization checks on messages received via leafnode connections. While ordinary client connections are checked properly, leafnode connections bypass these checks, enabling a leafnode operator to send trace events to subjects that would normally be restricted. This can be exploited to use trace-only behavior to prevent the normal delivery or storage of messages on those subjects. The issue is addressed in versions 2.14.3 and 2.12.8.
Potential Impact
An attacker with leafnode operator privileges can send trace events to unauthorized subjects, potentially interfering with message delivery or storage by leveraging trace-only behavior. This could disrupt normal messaging operations within the affected NATS Server deployments.
Mitigation Recommendations
This vulnerability is fixed in nats-server versions 2.14.3 and 2.12.8. Users should upgrade to at least these versions to remediate the issue. No other mitigation or temporary workaround is indicated in the available data.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-06-29T21:54:30.330Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a4eafe9c9d9e3dbe3adea8f
Added to database: 07/08/2026, 20:15:37 UTC
Last enriched: 07/16/2026, 10:13:32 UTC
Last updated: 08/22/2026, 10:52:10 UTC
Views: 61
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