NATS Server: Incomplete fix for CVE-2026-33249: Leaf node connections bypass Nats-Trace-Dest permission check (CVE-2026-58254)
NATS Server versions prior to 2.14.3 and 2.12.8 have an incomplete fix for a permission check bypass in leaf node connections related to message trace destination. This allows a leafnode operator to send trace events to unauthorized subjects and potentially interfere with normal message delivery or storage. The issue is resolved in versions 2.14.3 and 2.12.8.
AI Analysis
Technical Summary
NATS Server, a messaging system server, had a vulnerability where message trace destination permission checks were inconsistently applied to messages arriving via leafnode connections. This allowed leafnode operators to bypass the Nats-Trace-Dest permission check, enabling them to send trace events to subjects they would not normally have permission to access. Additionally, this trace-only behavior could be used to prevent normal delivery or storage of affected messages. The vulnerability affects versions prior to 2.14.3 and 2.12.8 and was fixed in those versions.
Potential Impact
An attacker with control over a leafnode connection could bypass permission checks on message trace destinations, potentially sending trace events to unauthorized subjects. This could also be used to disrupt normal message delivery or storage by leveraging trace-only behavior. There is no indication of known exploits in the wild.
Mitigation Recommendations
A fix is available in NATS Server versions 2.14.3 and 2.12.8. Users should upgrade to these versions or later to remediate this vulnerability.
NATS Server: Incomplete fix for CVE-2026-33249: Leaf node connections bypass Nats-Trace-Dest permission check (CVE-2026-58254)
Description
NATS Server versions prior to 2.14.3 and 2.12.8 have an incomplete fix for a permission check bypass in leaf node connections related to message trace destination. This allows a leafnode operator to send trace events to unauthorized subjects and potentially interfere with normal message delivery or storage. The issue is resolved in versions 2.14.3 and 2.12.8.
Affected software
pkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=questingpkg:deb/ubuntu/[email protected]~esm1?arch=source&distro=esm-apps/resoluteRun 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 messaging system server, had a vulnerability where message trace destination permission checks were inconsistently applied to messages arriving via leafnode connections. This allowed leafnode operators to bypass the Nats-Trace-Dest permission check, enabling them to send trace events to subjects they would not normally have permission to access. Additionally, this trace-only behavior could be used to prevent normal delivery or storage of affected messages. The vulnerability affects versions prior to 2.14.3 and 2.12.8 and was fixed in those versions.
Potential Impact
An attacker with control over a leafnode connection could bypass permission checks on message trace destinations, potentially sending trace events to unauthorized subjects. This could also be used to disrupt normal message delivery or storage by leveraging trace-only behavior. There is no indication of known exploits in the wild.
Mitigation Recommendations
A fix is available in NATS Server versions 2.14.3 and 2.12.8. Users should upgrade to these versions or later to remediate this vulnerability.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- UBUNTU-CVE-2026-58254
- Osv Schema Version
- 1.7.0
- Ecosystems
- ["Ubuntu:24.04:LTS","Ubuntu:25.10","Ubuntu:Pro:26.04:LTS"]
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6a58b45d68715ace43d6be21
Added to database: 07/16/2026, 10:37:17 UTC
Last enriched: 09/08/2026, 15:19:10 UTC
Last updated: 09/10/2026, 20:22:42 UTC
Views: 20
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