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GHSA-g6w6-r76c-28j7
No affected components available
(This advisory is canonically https://advisories.nats.io/CVE/CVE-2022-24450.txt)
Problem Description
NATS nats-server through 2022-02-04 has Incorrect Access Control, with unchecked ability for clients to authorize into any account, because of a coding error in a long-extant experimental feature.
A client crafting the initial protocol-level handshake could, with valid credentials for any account, specify a target account and switch into it immediately. This includes any other tenant, and includes the System account which controls nats-server core operations.
For deployments not using multi-tenancy through NATS Accounts, there is still a vulnerability: normal users are able to choose to be in the System account.
An experimental feature to provide dynamically provisioned sandbox accounts was designed to allow a server administrator to turn on an option to allow clients to dynamically request a brand new account inline at connection time. This feature went nowhere, but lived on in the code and was used by a number of tests; support was never added to any client libraries or to the documentation.
A bug in handling the feature meant that if someone did in fact have valid account credentials, then they could specify any other existing account and they would be assigned into that account.
Release 2.7.2 of nats-server removes the feature. Because of the lack of client support and absence from protocol documentation, we feel this is safe operationally as well as the safest fix for the code.
Affected versions
NATS Server
- All 2.x versions up to and including 2.7.1.
- Fixed with nats-io/nats-server: 2.7.2
- NATS Server 1.x did not have accounts.
- Docker image: nats https://hub.docker.com/_/nats
NATS Streaming Server
- All versions embedding affected NATS Server:
- Affected: v0.15.0 up to and including v0.24.0
- Fixed with nats-io/nats-streaming-server: 0.24.1
- Docker image: nats-streaming https://hub.docker.com/_/nats-streaming
Impact
Existing users could act in any account, including the System account.
Workaround
None.
Solution
Upgrade the NATS server.
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the confidentiality of the information. There is a high impact on the integrity of the data. There is a high impact on the availability of the system.
Exploitation activity has been observed. Apply available patches or mitigations urgently.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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