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NATS: Leafnode connections allow spoofing of Nats-Request-Info identity headers

CVSS 3.1 6.4 MEDIUMEUVD CVSS 3.1 6.4 CVSS 3.1 · [email protected] · Secondary 6.4 MEDIUMCVSS 3.1 · [email protected] · Primary 5.4 MEDIUMCVSS_V3 Publisher rating MODERATEFixed by github.com/nats-io/nats-server/v2 2.11.15Fixed by github.com/nats-io/nats-server/v2 2.12.6osv · severity unknownFixed by github.com/nats-io/nats-server/v2 2.11.15Fixed by github.com/nats-io/nats-server/v2 2.12.6KEV status unknown

cve-program · CVE-2026-33246

Published

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The nats-server offers a `Nats-Request-Info:` message header, providing information about a request. This is supposed to provide enough information to allow for account/user identification, such that NATS clients could make their own decisions on how to trust a message, provided that they trust the nats-server as a broker. A leafnode connecting to a nats-server is not fully trusted unless the system account is bridged too. Thus identity claims should not have propagated unchecked. Prior to versions 2.11.15 and 2.12.6, NATS clients relying upon the Nats-Request-Info: header could be spoofed. This does not directly affect the nats-server itself, but the CVSS Confidentiality and Integrity scores are based upon what a hypothetical client might choose to do with this NATS header. Versions 2.11.15 and 2.12.6 contain a fix. No known workarounds are available.

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euvd · EUVD-2026-15973

Published

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The nats-server offers a `Nats-Request-Info:` message header, providing information about a request. This is supposed to provide enough information to allow for account/user identification, such that NATS clients could make their own decisions on how to trust a message, provided that they trust the nats-server as a broker. A leafnode connecting to a nats-server is not fully trusted unless the system account is bridged too. Thus identity claims should not have propagated unchecked. Prior to versions 2.11.15 and 2.12.6, NATS clients relying upon the Nats-Request-Info: header could be spoofed. This does not directly affect the nats-server itself, but the CVSS Confidentiality and Integrity scores are based upon what a hypothetical client might choose to do with this NATS header. Versions 2.11.15 and 2.12.6 contain a fix. No known workarounds are available.

Read the publisher's advisory

nvd · CVE-2026-33246

Published

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The nats-server offers a `Nats-Request-Info:` message header, providing information about a request. This is supposed to provide enough information to allow for account/user identification, such that NATS clients could make their own decisions on how to trust a message, provided that they trust the nats-server as a broker. A leafnode connecting to a nats-server is not fully trusted unless the system account is bridged too. Thus identity claims should not have propagated unchecked. Prior to versions 2.11.15 and 2.12.6, NATS clients relying upon the Nats-Request-Info: header could be spoofed. This does not directly affect the nats-server itself, but the CVSS Confidentiality and Integrity scores are based upon what a hypothetical client might choose to do with this NATS header. Versions 2.11.15 and 2.12.6 contain a fix. No known workarounds are available.

Read the publisher's advisory

osv · GHSA-55h8-8g96-x4hj

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 allows hub/spoke topologies using "leafnode" connections by other nats-servers. NATS messages can have headers. ### Problem Description The nats-server offers a `Nats-Request-Info:` message header, providing information about a request. This is supposed to provide enough information to allow for account/user identification, such that NATS clients could make their own decisions on how to trust a message, provided that they trust the nats-server as a broker. A leafnode connecting to a nats-server is not fully trusted unless the system account is bridged too. Thus identity claims should not have propagated unchecked. Thus NATS clients relying upon the Nats-Request-Info: header could be spoofed. Does not directly affect the nats-server itself, but the CVSS Confidentiality and Integrity scores are based upon what a hypothetical client might choose to do with this NATS header. ### Affected Versions Any version before v2.12.6 or v2.11.15 ### Workarounds None.

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osv · GO-2026-4830

Published

NATS: Leafnode connections allow spoofing of Nats-Request-Info identity headers in github.com/nats-io/nats-server

Read the publisher's advisory

Affected versions, risk and source history

Exploitation and risk

Source status

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Risk history

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Advisory history

14 saved versions

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15 Nov 2026 10:02:40 UTC

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The nats-server offers a `Nats-Request-Info:` message header, providing information about a request. This is supposed to provide enough informat…

euvd · EUVD-2026-15973 · Published

13 Nov 2026 09:06:03 UTC

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The nats-server offers a `Nats-Request-Info:` message header, providing information about a request. This is supposed to provide enough informat…

euvd · EUVD-2026-15973 · Published

11 Nov 2026 08:36:06 UTC

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The nats-server offers a `Nats-Request-Info:` message header, providing information about a request. This is supposed to provide enough informat…

euvd · EUVD-2026-15973 · Published

9 Nov 2026 08:10:09 UTC

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The nats-server offers a `Nats-Request-Info:` message header, providing information about a request. This is supposed to provide enough informat…

euvd · EUVD-2026-15973 · Published

7 Nov 2026 07:34:06 UTC

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The nats-server offers a `Nats-Request-Info:` message header, providing information about a request. This is supposed to provide enough informat…

euvd · EUVD-2026-15973 · Published

5 Nov 2026 07:02:53 UTC

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The nats-server offers a `Nats-Request-Info:` message header, providing information about a request. This is supposed to provide enough informat…

euvd · EUVD-2026-15973 · Published

3 Nov 2026 06:06:29 UTC

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The nats-server offers a `Nats-Request-Info:` message header, providing information about a request. This is supposed to provide enough informat…

euvd · EUVD-2026-15973 · Published

1 Nov 2026 05:12:48 UTC

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The nats-server offers a `Nats-Request-Info:` message header, providing information about a request. This is supposed to provide enough informat…

euvd · EUVD-2026-15973 · Published

30 Oct 2026 04:56:57 UTC

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The nats-server offers a `Nats-Request-Info:` message header, providing information about a request. This is supposed to provide enough informat…

euvd · EUVD-2026-15973 · Published

28 Oct 2026 03:58:34 UTC

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The nats-server offers a `Nats-Request-Info:` message header, providing information about a request. This is supposed to provide enough informat…

euvd · EUVD-2026-15973 · Published

25 Oct 2026 08:17:18 UTC

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The nats-server offers a `Nats-Request-Info:` message header, providing information about a request. This is supposed to provide enough informat…

nvd · CVE-2026-33246 · Published

24 Oct 2026 13:19:41 UTC

NATS: Leafnode connections allow spoofing of Nats-Request-Info identity headers

osv · GHSA-55h8-8g96-x4hj · Published

24 Oct 2026 13:19:41 UTC

NATS: Leafnode connections allow spoofing of Nats-Request-Info identity headers in github.com/nats-io/nats-server

osv · GO-2026-4830 · Published

23 Oct 2026 15:48:27 UTC

NATS: Leafnode connections allow spoofing of Nats-Request-Info identity headers

cve-program · CVE-2026-33246 · Published

ChangeIntel

An IT change radar: releases, security, known issues, retirements, documentation changes, and service status from public sources. Every item links to supporting evidence; dates and statuses can change after they are read.

Sources read 15 Nov 12:11 UTC · 256 of 275 readable · 252 fully read · documentation 469/469 current