VulnerabilityPublished 25 Mar 2026Updated 9 Sep 2026

CVE-2026-33216: nats-server · Plaintext Storage of a Password

Affects nats-serverSource CVE Database V5

Compare

Not known to be exploited · CVSS 8.6 High : upgrade to 2.12.6 or 2.11.15 soon.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 3.1 base score

8.6High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.3% chance of exploitation in 30 days – higher than 31% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 2.12.6, 2.11.15

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

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 25 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade nats-server to 2.12.6 or 2.11.15; nats-io/nats-server to 2.11.15.

Affected software

Product	Affected	Fixed in
nats-ionats-server	Affected >=2.12.0-RC.1 <2.12.6	Fixed in 2.12.6
nats-ionats-server	Affected <2.11.15	Fixed in 2.11.15
GitHubnats-io/nats-server`pkg:github/nats-io/nats-server`Other threats	Affected <2.11.15	Fixed in 2.11.15

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix is available in nats-server versions 2.11.15 and 2.12.6. Users should upgrade to these or later versions to remediate the vulnerability. As a workaround, ensure that monitoring endpoints are adequately secured and not exposed to untrusted networks or the Internet. The vendor advisory indicates that other mitigations do not meet criteria for broad applicability or stability.

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, for MQTT deployments using usercodes/passwords: MQTT passwords are incorrectly classified as a non-authenticating identity statement (JWT) and exposed via monitoring endpoints. Versions 2.11.14 and 2.12.6 contain a fix. As a workaround, ensure monitoring end-points are adequately secured. Best practice remains to not expose the monitoring endpoint to the Internet or other untrusted network users.

Impact

An attacker with network access to the monitoring endpoints can obtain MQTT passwords due to their exposure in plaintext. This compromises confidentiality but does not affect integrity or availability of the system. The vulnerability allows unauthorized disclosure of sensitive authentication credentials, which could lead to further unauthorized access if exploited.

Summary

NATS-Server versions prior to 2.11.15 and 2.12.6 contain a vulnerability where MQTT passwords are incorrectly treated as non-authenticating identity statements (JWT). This misclassification causes the passwords to be exposed through monitoring endpoints, which can be accessed by attackers with network access to these endpoints. The vulnerability is identified as CWE-256 (Plaintext Storage of a Password) and CWE-213 (Information Exposure Through Discrepant Handling). The issue is fixed in versions 2.11.15 and 2.12.6. The vulnerability has a CVSS v3.1 score of 8.6 (AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N), indicating network attack vector, low complexity, no privileges or user interaction required, changed scope, and high confidentiality impact without integrity or availability impact. No known exploits in the wild have been reported. The vendor advisory notes that mitigation options other than upgrading do not meet criteria for ease of use and applicability, but recommends securing monitoring endpoints as a workaround.

CWE-256Plaintext Storage of a Password (opens in a new tab)
Base weaknessLikelihood of exploit: HighOWASP Top 10 A06:2025: Insecure Design (opens in a new tab)
The product stores a password in plaintext within resources such as memory or files.
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.
OWASP Cheat Sheets
Forgot Password (opens in a new tab)
Secure Design Principles (opens in a new tab)
OWASP ASVS 4.0.3
V2.7.5 (opens in a new tab)
V2.8.5 (opens in a new tab)
V2.8.4 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-213Exposure of Sensitive Information Due to Incompatible Policies (opens in a new tab)
Base weaknessOWASP Top 10 A04:2021: Insecure Design (opens in a new tab)
The product's intended functionality exposes information to certain actors in accordance with the developer's security policy, but this information is regarded as sensitive according to the intended security policies of other stakeholders such as the product's administrator, users, or others whose information is being processed.
Requirements · Architecture and Design
When handling information, the developer must consider whether the information is regarded as sensitive by different stakeholders, such as users or administrators. Each stakeholder effectively has its own intended security policy that the product is expected to uphold.
OWASP Cheat Sheets
Error Handling (opens in a new tab)
Logging (opens in a new tab)
OWASP ASVS 4.0.3
V8.3.4 (opens in a new tab)
V14.3.3 (opens in a new tab)
V7.3.3 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 13 Aug 2026, 16:32 UTC

WeaknessesCWE-256, CWE-213

Technical details

References

Community reviews

Related threats