CVE-2026-33246

mediumpriority · track · 22EPSS 0.001 · 4 %ileDEEUUS
grimoire priorityP3 · Track
Exploitable?
—
no known exploitation
Likely / severe?
0.15% (4th) EPSS
CVSS 5.4 · medium
Is it mine?
14 products
Check your exposure
Who says so?
5 sources
cnnvd · enisa_euvd · osv · cert_bund

EPSS · scored 2026-10-27

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.

01

cvss

Technical severity, 0–10. One row per scoring source.

6.4
010

base score 0–10 · higher = more severe · hover a vector to decode

v3.15.4mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:Nprimary · NVD / NIST USexploitability 2.8 · impact 2.5
v3.16.4mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:Nsecondary · ENISA EU
v3.16.4mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:Nsecondary · security-advisories@github.comexploitability 3.1 · impact 2.7
v3.16.4mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:Nsecondary · OSV
v3.15mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N/E:Usecondary · CVSS-BT (t0sche)
02

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Trackcoordinatorcisa_ssvcUS
03

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-287USCWE-287USCWE-290USCWE-290US
04

affected products (14)

Products and version ranges known to be affected.

05

advisories (4)

Vendor and ecosystem advisories describing this.

  • WID-SEC-W-2026-0858NATS Server: Mehrere SchwachstellenDeutsch2026-03-24csaf · cert_bundDE

    Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in NATS Server ausnutzen, um Informationen offenzulegen oder zu manipulieren, einen Denial-of-Service zu verursachen und Sicherheitsmechanismen zu umgehen.

  • GHSA-55h8-8g96-x4hjNATS: Leafnode connections allow spoofing of Nats-Request-Info identity headers2026-03-24ghsa · osvUS

    ### 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.

  • BIT-nats-2026-33246NATS: Leafnode connections allow spoofing of Nats-Request-Info identity headers2026-03-27vendor · osvUS

    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.

  • GO-2026-4830NATS: Leafnode connections allow spoofing of Nats-Request-Info identity headers in github.com/nats-io/nats-server2026-03-26vendor · osvUS

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

06

also known as (6)

Other names and identifiers for this entity.

07

sources

Which sources assert this record, and when.

cnnvdenisa_euvdosvcert_bundnvdNVDCVE.orgMITRE
published 2026-03-25modified 2026-06-17
08

references (8)

External citations — patches, advisories, analysis.

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