Impacted: Liminal Express SDK v1.2.19 and above.
The previously introduced feature, for Whitelisted Express IP in API Key [Wallet v1 & v2] during the Vaults: November 04, 2025 release [Wallet v1 & v2], is now marked as a breaking change for Liminal Express SDK v1.2.19 [Wallet v1 & v2] and above.
It is now mandatory to add the EXPRESS_OUTBOUND_IP value to your local MPC Docker image when the Express server IP address is whitelisted on Vaults, and the deployment environment is behind a payload.
What Changed (Earlier Release)
The following changes were implemented in the previous November major release [Wallet v1 & v2]:
- The following IP addresses were added to the API Key whitelist feature:
- Source IP, and
- Express server IP.
- Additionally, the HMAC secret key feature required adding the
HMAC_SECRETvalue in the following configurations:- Vaults web > Apps > Secure API
- The
.envfile of the client’s Docker image (express.sh) of the Liminal Express SDK.
- Required at least a Liminal Express SDK version:
v1.2.19(Prod) or higher.
Why is this a breaking change
Users may experience a breaking change if the required parameters are not configured when:
- Their deployment server environment is behind a load balancer.
- Using Liminal Express version
v1.2.19or higher. - Have whitelisted at least one Express IP address on Vaults.
When your server-side Liminal Express deployment is configured behind a load balancer, the Express IP address acts as a dynamic address, preventing it from being whitelisted in Vaults. Then, the Liminal Express APIs may break, and the whitelisted Express IP address may not function accurately.
Added Requirement
When your Express server is behind a load balancer, the following parameters should be added to the MPC Docker image (express.sh):
| Parameter | Required / Recommended | Data Type | Description | When is it required |
|---|---|---|---|---|
EXPRESS_OUTBOUND_IP | Required | String | The IP address of the Liminal Express server (x-express-ip). | When the Liminal Express SDK deployment is behind a load balancer in the Production environment. |
HMAC_SECRET | Recommended | String | Shared secret key for HMAC authentication between Liminal Express API and the client application. The key must be 20–64 alphanumeric characters. | All instances of the Production environment. |
Impact
After upgrading to the latest Liminal Express version 1.2.19 ( or higher):
- All API requests from Liminal Express SDK (both server and client) will fail if
EXPRESS_OUTBOUND_IPis not added to your Docker image. - The whitelisted Express IP address (
EXPRESS_OUTBOUND_IP) will not function as expected and accept server requests. - Existing integrations based on API key will break.
Required Action
Ensure that you:
-
Update the Docker image (
express.sh): Add theEXPRESS_OUTBOUND_IP(required) andHMAC_SECRET(recommended) values to the.envfile.
Sample Docker image:docker run --restart=on-failure \ -e AWS_DEFAULT_REGION=ap-south-1 \ -e REGION=ap-south-1 \ -e NODE_ENV=prod \ -e TSM_URL=http://172.31.3.30:8000 \ -e TSM_VERSION=62 \ -e TSM_USER_ID=test-user-123 \ -e HMAC_SECRET=TESTHMACSECRETKEY1234567890 \ -e TSM_PASSWORD=StrongPass!2025 \ -e TSM_PUBLIC_KEY=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAr4w7Z6q1W0z7f6qT3hRL \ -e AUTH_URL=https://vaults-secure.us.auth0.com/oauth/token \ -e AUTH_AUDIENCE=https://api.lmnl.app/api/wallet/all \ -e EXPRESS_OUTBOUND_IP=3.110.45.120 \ -p 8081:8081 \ -d 641754881946.dkr.ecr.us-west-2.amazonaws.com/liminal-sdk-api:1-stable-prod -
Restart and rerun the Docker image (
express.sh) after successfully embedding the required environment variables. -
Add HMAC key to Liminal Vaults: Liminal Vaults> Apps > Secure API.
Have added the same HMAC secret key for both the MPC Docker image and Vaults to ensure the necessary whitelisted IP addresses function accurately, if using the HMAC secret authentication.
References
- Refer to the Whitelist IP Address per Key > Caveat [wallet v1 & v2] section to update your Docker image as required.
- Refer to the Liminal Express API changelog [wallet v1 & v2] for the latest production version.
- Refer to the How to setup HMAC secret key and boost IP whitelisting security with SecureAPI guide [wallet v1 & v2] to configure HMAC security authentication.
- Update Express SDK version [wallet v1 & v2].
