BIT-nats-2021-3127

Affected: Bitnami: nats

NATS Server 2.x before 2.2.0 and JWT library before 2.0.1 have Incorrect Access Control because Import Token bindings are mishandled.

cnvd-2021-26378

EUVD-2026-20699

fkie_cve-2021-3127

NATS Server 2.x before 2.2.0 and JWT library before 2.0.1 have Incorrect Access Control because Import Token bindings are mishandled.

GHSA-62mh-w5cv-p88c — nats-io/jwt not enforcing checking of Import token permissions

Affected: Go: github.com/nats-io/jwt, Go: github.com/nats-io/jwt/v2

(This advisory is canonically <https://advisories.nats.io/CVE/CVE-2021-3127.txt>)

## Problem Description

The NATS server provides for Subjects which are namespaced by Account; all Subjects are supposed to be private to an account, with an Export/Import system used to grant cross-account access to some Subjects. Some Exports are public, such that anyone can import the relevant subjects, and some Exports are private, such that the Import requires a token JWT to prove permission.

The JWT library's validation of the bindings in the Import Token incorrectly warned on mismatches, instead of outright rejecting the token.

As a result, any account can take an Import token used by any other account and re-use it for themselves because the binding to the importing account is not rejected, and use it to import *any* Subject from the Exporting account, not just the Subject referenced in the Import Token.

The NATS account-server system treats account JWTs as semi-public information, such that an attacker can easily enumerate all account JWTs and retrieve all Import Tokens from those account JWTs.

The CVE identifier should cover the JWT library repair and the nats-server containing the fixed JWT library, and any other application depending upon the fixed JWT library.

## Affected versions

#### JWT library

* all versions prior to 2.0.1 * fixed after nats-io/jwt#149 landed (2021-03-14)

#### NATS Server

* Version 2 prior to 2.2.0 + 2.0.0 through and including 2.1.9 are vulne…

UBUNTU-CVE-2021-3127

Affected: Ubuntu:20.04:LTS: golang-github-nats-io-jwt, Ubuntu:22.04:LTS: golang-github-nats-io-jwt

NATS Server 2.x before 2.2.0 and JWT library before 2.0.1 have Incorrect Access Control because Import Token bindings are mishandled.

Most recent entries from all

BIT-nats-2021-3127

cnvd-2021-26378

EUVD-2026-20699

fkie_cve-2021-3127

GHSA-62mh-w5cv-p88c — nats-io/jwt not enforcing checking of Import token permissions

gsd-2021-3127

UBUNTU-CVE-2021-3127