GHSA-v722-jcv5-w7mc BIT-nats-2026-33216 CVE-2026-33216 GO-2026-4836
NATS has MQTT plaintext password disclosure
- Severity
- 8.6 / 10
- High · CVSS 3.1
- Exploit chance (EPSS)
- 0.37%
- Chance of exploitation in the next 30 days. Higher than 31.13% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-256 Plaintext Storage of a Password
- Fix
2.11.15- Upgrade github.com/nats-io/nats-server/v2 to this version or later
Description
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 provides an MQTT client interface.
Problem Description
For MQTT deployments using usercodes/passwords: MQTT passwords are incorrectly classified as a non-authenticating identity statement (JWT) and exposed via monitoring endpoints.
Affected Versions
Any version before v2.12.6 or v2.11.15
Workarounds
Ensure monitoring end-points are adequately secured.
Best practice remains to not expose the monitoring endpoint to the Internet or other untrusted network users.
Affected versions
Go
| Package | Vulnerable | Fixed in |
|---|---|---|
| github.com/nats-io/nats-server | all versions |
No fix yet |
| github.com/nats-io/nats-server/v2 | < 2.11.15 |
2.11.15 |
| github.com/nats-io/nats-server/v2 | >= 2.12.0-RC.1, < 2.12.6 |
2.12.6 |
| github.com/nats-io/nats-server/v2 | < 2.11.15>= 2.12.0-RC.1, < 2.12.6 |
2.11.152.12.6 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
github.com/nats-io/nats-server/v2 Go → 2.11.15
- go
go get github.com/nats-io/nats-server/v2@v2.11.15 && go mod tidy
Severity breakdown
CVSS 3.1 8.6
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Changed
- Confidentiality
- High
- Integrity
- None
- Availability
- None
Weakness
CWE-256: Plaintext Storage of a Password
The product stores a password in plaintext within resources such as memory or files.
How to prevent it
- Architecture and Design: Avoid storing passwords in easily accessible locations.
- Architecture and Design: Consider storing cryptographic hashes of passwords as an alternative to storing in plaintext.
- A programmer might attempt to remedy the password management problem by obscuring the password with an encoding function, such as base 64 encoding, but this effort does not adequately protect the password because the encoding can be detected and decoded easily.
References
Advisories
Packages
Other links
- github.com/nats-io/nats-server/security/advisories/GHSA-v722-jcv5-w7mc
- github.com/nats-io/nats-server/commit/b5b63cfc35a57075e09c1f57503d31721bed8099
- advisories.nats.io/CVE/secnote-2026-05.txt
- access.redhat.com/errata/RHSA-2026:21769
- access.redhat.com/errata/RHSA-2026:22347
- access.redhat.com/errata/RHSA-2026:23345
- access.redhat.com/security/cve/CVE-2026-33216
- bugzilla.redhat.com/show_bug.cgi
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33216.json
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-pq2q-rcw4-3hr6 NATS: Pre-auth remote server crash via WebSocket frame length overflow in wsRead | High | Also affects github.com/nats-io/nats-server |
| GHSA-3f24-pcvm-5jqc NATS has mTLS verify_and_map authentication bypass via incorrect Subject DN matching | Medium | Also affects github.com/nats-io/nats-server |
| GHSA-55h8-8g96-x4hj NATS: Leafnode connections allow spoofing of Nats-Request-Info identity headers | Medium | Also affects github.com/nats-io/nats-server |
| GHSA-pwx7-fx9r-hr4h NATS Server: Incomplete Stripping of Nats-Request-Info Header Allows Identity Spoofing | Medium | Also affects github.com/nats-io/nats-server |
| GHSA-9983-vrx2-fg9c NATS JetStream has an authorization bypass through its Management API | Medium | Also affects github.com/nats-io/nats-server |
| GHSA-8r68-gvr4-jh7j NATS is vulnerable to pre-auth DoS through WebSockets client service | Medium | Also affects github.com/nats-io/nats-server |
| GHSA-vprv-35vv-q339 NATS has pre-auth server panic via leafnode handling | High | Also affects github.com/nats-io/nats-server |
| GHSA-jxxm-27vp-c3m5 NATS allows MQTT clients to bypass ACL checks | Medium | Also affects github.com/nats-io/nats-server |
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