CVE-2026-33249

NATS: Message tracing can be redirected to arbitrary subject

CVSS 3.1 4.3 MEDIUMEUVD CVSS 3.1 4.3 CVSS 3.1 · [email protected] · Secondary 4.3 MEDIUMCVSS_V3 Publisher rating MODERATEFixed by github.com/nats-io/nats-server/v2 2.11.15 Fixed by github.com/nats-io/nats-server/v2 2.12.6osv · severity unknownFixed by github.com/nats-io/nats-server/v2 2.11.15 Fixed by github.com/nats-io/nats-server/v2 2.12.6KEV status unknown

Original advisory

cve-program · CVE-2026-33249

Published

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Starting in version 2.11.0 and prior to versions 2.11.15 and 2.12.6, 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 chosen by the attacker. Versions 2.11.15 and 2.12.6 contain a fix. No known workarounds are available.

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euvd · EUVD-2026-16000

Published

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nvd · CVE-2026-33249

Published

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osv · GHSA-8m2x-3m6q-6w8j

Published

### Background NATS.io is a high performance open source pub-sub distributed communication technology, built for the cloud, on-premise, IoT, and edge computing. The nats-server supports telemetry on messages, using the per-message NATS headers. ### Problem Description 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 chosen by the attacker. ### Affected Versions Any version before v2.12.6 or v2.11.15 ### Workarounds None.

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osv · GO-2026-4826

Published

NATS: Message tracing can be redirected to arbitrary subject in github.com/nats-io/nats-server

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Affected versions, risk and source history

Exploitation and risk

Source status

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Risk history

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Advisory history

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15 Nov 2026 10:02:42 UTC