The vulnerability is that IDToken verifier does not verify if token is properly signed. Signature verification makes sure that the token's payload comes from valid provider, not from someone else. An attacker can provide a compromised token with custom payload. The token will pass the validation on the client side. We recommend upgrading to version 1.33.3 or above

Affected: Maven: com.google.oauth-client:google-oauth-client

### Summary The vulnerability impacts only users of the `IdTokenVerifier` class. The verify method in `IdTokenVerifier` does not validate the signature before verifying the claims (e.g., iss, aud, etc.). Signature verification makes sure that the token's payload comes from valid provider, not from someone else.

An attacker can provide a compromised token with modified payload like email or phone number. The token will pass the validation by the library. Once verified, modified payload can be used by the application.

If the application sends verified `IdToken` to other service as is like for auth - the risk is low, because the backend of the service is expected to check the signature and fail the request.

Reporter: [Tamjid al Rahat](https://github.com/tamjidrahat), contributor

### Patches The issue was fixed in the 1.33.3 version of the library

### Proof of Concept To reproduce, one needs to call the verify function with an IdToken instance that contains a malformed signature to successfully bypass the checks inside the verify function.

``` /** A default http transport factory for testing */ static class DefaultHttpTransportFactory implements HttpTransportFactory { public HttpTransport create() { return new NetHttpTransport(); } }

// The below token has some modified bits in the signature private static final String SERVICE_ACCOUNT_RS256_TOKEN_BAD_SIGNATURE = "eyJhbGciOiJSUzI1NiIsImtpZCI6IjJlZjc3YjM4YTFiMDM3MDQ4NzA0MzkxNmFjYmYyN2Q3NG" + "VkZD…

Affected: openEuler:24.03-LTS: google-oauth-java-client

Written by Google, the Google OAuth Client Library for Java is a powerful and easy-to-use Java library for the OAuth 1.0a and OAuth 2.0 authorization standards. The Google OAuth Client Library for Java is designed to work with any OAuth service on the web, not just with Google APIs. It is built on the Google HTTP Client Library for Java. Security Fix(es):

The vulnerability is that IDToken verifier does not verify if token is properly signed. Signature verification makes sure that the token's payload comes from valid provider, not from someone else. An attacker can provide a compromised token with custom payload. The token will pass the validation on the client side. We recommend upgrading to version 1.33.3 or above(CVE-2021-22573)

google-oauth-client: Token signature not verified

Security update for google-oauth-java-client

Affected: Ubuntu:22.04:LTS: google-oauth-client-java, Ubuntu:24.04:LTS: google-oauth-client-java, Ubuntu:25.10: google-oauth-client-java, Ubuntu:26.04:LTS: google-oauth-client-java

The vulnerability is that IDToken verifier does not verify if token is properly signed. Signature verification makes sure that the token's payload comes from valid provider, not from someone else. An attacker can provide a compromised token with custom payload. The token will pass the validation on the client side. We recommend upgrading to version 1.33.3 or above

Ein entfernter, anonymer, authentisierter oder lokaler Angreifer kann mehrere Schwachstellen in Red Hat FUSE ausnutzen, um vertrauliche Informationen offenzulegen, beliebigen Code auszuführen, einen Denial of Service Zustand herbeizuführen, Sicherheitsmaßnahmen zu umgehen, Daten und Informationen zu manipulieren und seine Privilegien zu erweitern.