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NATS: Message tracing can be redirected to arbitrary subject

Moderate severity GitHub Reviewed Published Mar 24, 2026 in nats-io/nats-server • Updated Mar 24, 2026

Package

gomod github.com/nats-io/nats-server/v2 (Go)

Affected versions

>= 2.11.0, < 2.11.15
>= 2.12.0-preview.1, < 2.12.6

Patched versions

2.11.15
2.12.6

Description

Impact

A valid client which uses message tracing headers can indicate that the trace messages can be sent to an arbitrary valid subject, including those to which the client does not have publish permission. The payload is a valid trace message and not attacker chosen.

Patches

Fixed in nats-server 2.12.6 & 2.11.15

Workarounds

None safe to use.

References

@philpennock philpennock published to nats-io/nats-server Mar 24, 2026
Published to the GitHub Advisory Database Mar 24, 2026
Reviewed Mar 24, 2026
Last updated Mar 24, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

EPSS score

Weaknesses

Incorrect Authorization

The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. Learn more on MITRE.

CVE ID

CVE-2026-33249

GHSA ID

GHSA-8m2x-3m6q-6w8j

Source code

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