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Client TLS credentials sent raw to server in npm package natsGHSA-prmc-5v5w-c465

GHSA-prmc-5v5w-c465 is a security vulnerability in nats. A fix is available for nats — see the affected versions and patch details below.

Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Mar 31, 2021 · OSV.dev, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, a proxy for how much of the ecosystem is exposed.

natsnpm
1.4Mdownloads / week

Description

Nats is a Node.js client for the NATS messaging system.

Problem Description

Preview versions of two NPM packages and one Deno package from the NATS project contain an information disclosure flaw, leaking options to the NATS server; for one package, this includes TLS private credentials.

The connection configuration options in these JavaScript-based implementations were fully serialized and sent to the server in the client's CONNECT message, immediately after TLS establishment.

The nats.js client supports Mutual TLS and the credentials for the TLS client key are included in the connection configuration options; disclosure of the client's TLS private key to the server has been observed.

Most authentication mechanisms are handled after connection, instead of as part of connection, so other authentication mechanisms are unaffected. For clarity: NATS account NKey authentication is NOT affected.

Neither the nats.ws nor the nats.deno clients support Mutual TLS: the affected versions listed below are those where the logic flaw is present. We are including the nats.ws and nats.deno versions out of an abundance of caution, as library maintainers, but rate as minimal the likelihood of applications leaking sensitive data.

Affected versions

Security impact

  • NPM package nats.js:
    • mainline is unaffected
    • beta branch is vulnerable from 2.0.0-201, fixed in 2.0.0-209

Logic flaw

  • NPM package nats.ws:

    • status: preview
    • flawed from 1.0.0-85, fixed in 1.0.0-111

  • Deno repository https://github.com/nats-io/nats.deno

    • status: preview
    • flawed in all git tags prior to fix
    • fixed with git tag v1.0.0-9

Impact

For deployments using TLS client certificates (for mutual TLS), private key material for TLS is leaked from the client application to the server. If the server is untrusted (run by a third party), or if the client application also disables TLS verification (and so the true identity of the server is unverifiable) then authentication credentials are leaked.

Workaround

None

Solution

Upgrade your package dependencies to fixed versions, and then reissue any TLS client credentials (with new keys, not just new certificates) and revoke the old ones.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
📦npmnats≥ 2.0.0-201&&< 2.0.0-2092.0.0-209npm install nats@2.0.0-209

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for nats, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update nats to 2.0.0-209 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-prmc-5v5w-c465 is resolved across your whole dependency graph.

  3. Workarounds

    Assume what was exposed is already known: rotate any credential, token or key that the affected component could return, restrict the endpoint to callers that genuinely need it, and strip sensitive fields from responses and error output at the boundary rather than relying on the client not to read them.

Frequently Asked Questions

Nats is a Node.js client for the NATS messaging system. ## Problem Description _Preview versions_ of two NPM packages and one Deno package from the NATS project contain an information disclosure flaw, leaking options to the NATS server; for one package, this includes TLS private credentials. The _connection_ configuration options in these JavaScript-based implementations were fully serialized and sent to the server in the client's `CONNECT` message, immediately after TLS establishment. The nats.js client supports Mutual TLS and the credentials for the TLS client key are included in the con
O3 Security · Impact-Aware SCA

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