CVE-2026-33223

NATS Server: Incomplete Stripping of Nats-Request-Info Header Allows Identity Spoofing

MEDIUM
5.4
CVSS Score
Published: March 25, 2026 at 08:20 PM UTC
Updated: June 17, 2026 at 10:37 AM UTC
2 products affected across 2 vendorsNats ServerNats Server

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Severity
MEDIUM5.4
Exploit prediction
EPSS 0.2%
SSVC
No known exploit

Description

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versions 2.11.15 and 2.12.6, the NATS message header `Nats-Request-Info:` is supposed to be a guarantee of identity by the NATS server, but the stripping of this header from inbound messages was not fully effective. An attacker with valid credentials for any regular client interface could thus spoof their identity to services which rely upon this header. Versions 2.11.15 and 2.12.6 contain a fix. No known workarounds are available.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 2.11.152.12.0 ≤ v < 2.12.6
v < 2.11.15v < 2.12.6
Affected range stops below 2.11.15, so it looks safe — our inference, not a vendor statement
Affected range stops below 2.12.6, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (2)

x_refsource_MISCVendor Advisory
Source: cverecord
https://advisories.nats.io/CVE/secnote-2026-09.txt

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-290

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