fix: update module google.golang.org/grpc to v1.79.3 [security]

[renovate-bot]

This PR contains the following updates:

Package	Change	Age	Confidence
google.golang.org/grpc	v1.79.1 → v1.79.3

GitHub Vulnerability Alerts

CVE-2026-33186

Impact

What kind of vulnerability is it? Who is impacted?

It is an Authorization Bypass resulting from Improper Input Validation of the HTTP/2 :path pseudo-header.

The gRPC-Go server was too lenient in its routing logic, accepting requests where the :path omitted the mandatory leading slash (e.g., Service/Method instead of /Service/Method). While the server successfully routed these requests to the correct handler, authorization interceptors (including the official grpc/authz package) evaluated the raw, non-canonical path string. Consequently, "deny" rules defined using canonical paths (starting with /) failed to match the incoming request, allowing it to bypass the policy if a fallback "allow" rule was present.

Who is impacted?
This affects gRPC-Go servers that meet both of the following criteria:

1. They use path-based authorization interceptors, such as the official RBAC implementation in google.golang.org/grpc/authz or custom interceptors relying on info.FullMethod or grpc.Method(ctx).
2. Their security policy contains specific "deny" rules for canonical paths but allows other requests by default (a fallback "allow" rule).

The vulnerability is exploitable by an attacker who can send raw HTTP/2 frames with malformed :path headers directly to the gRPC server.

Patches

Has the problem been patched? What versions should users upgrade to?

Yes, the issue has been patched. The fix ensures that any request with a :path that does not start with a leading slash is immediately rejected with a codes.Unimplemented error, preventing it from reaching authorization interceptors or handlers with a non-canonical path string.

Users should upgrade to the following versions (or newer):

• v1.79.3
• The latest master branch.

It is recommended that all users employing path-based authorization (especially grpc/authz) upgrade as soon as the patch is available in a tagged release.

Workarounds

Is there a way for users to fix or remediate the vulnerability without upgrading?

While upgrading is the most secure and recommended path, users can mitigate the vulnerability using one of the following methods:

1. Use a Validating Interceptor (Recommended Mitigation)

Add an "outermost" interceptor to your server that validates the path before any other authorization logic runs:

func pathValidationInterceptor(ctx context.Context, req any, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (any, error) {
    if info.FullMethod == "" || info.FullMethod[0] != '/' {
        return nil, status.Errorf(codes.Unimplemented, "malformed method name")
    }   
    return handler(ctx, req)
}

// Ensure this is the FIRST interceptor in your chain
s := grpc.NewServer(
    grpc.ChainUnaryInterceptor(pathValidationInterceptor, authzInterceptor),
)

2. Infrastructure-Level Normalization

If your gRPC server is behind a reverse proxy or load balancer (such as Envoy, NGINX, or an L7 Cloud Load Balancer), ensure it is configured to enforce strict HTTP/2 compliance for pseudo-headers and reject or normalize requests where the :path header does not start with a leading slash.

3. Policy Hardening

Switch to a "default deny" posture in your authorization policies (explicitly listing all allowed paths and denying everything else) to reduce the risk of bypasses via malformed inputs.

---

Release Notes

grpc/grpc-go (google.golang.org/grpc)

v1.79.3: Release 1.79.3

Compare Source

Security

• server: fix an authorization bypass where malformed :path headers (missing the leading slash) could bypass path-based restricted "deny" rules in interceptors like grpc/authz. Any request with a non-canonical path is now immediately rejected with an Unimplemented error. (#​8981)

v1.79.2: Release 1.79.2

Compare Source

Bug Fixes

• stats: Prevent redundant error logging in health/ORCA producers by skipping stats/tracing processing when no stats handler is configured. (#​8874)

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[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request delivers an essential security update for the google.golang.org/grpc module, upgrading it to v1.79.3. This update is crucial for mitigating a recently discovered authorization bypass vulnerability that could affect gRPC-Go servers utilizing path-based authorization. Applying this patch ensures enhanced security by correctly handling malformed request paths, thereby preventing potential unauthorized access.

Highlights

• Dependency Update: Updated the google.golang.org/grpc module from v1.79.1 to v1.79.3 across various go.mod files.
• Security Fix: Addressed a critical authorization bypass vulnerability (CVE-2026-33186) in gRPC-Go servers related to improper input validation of HTTP/2 :path pseudo-headers.
• Vulnerability Mitigation: Implemented a fix that now immediately rejects requests with malformed :path headers (those missing a leading slash) with an Unimplemented error, preventing them from bypassing path-based authorization interceptors.

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[gemini-code-assist]

Code Review

This pull request updates the google.golang.org/grpc dependency from v1.79.1 to v1.79.3 across all modules within the repository. This is an important security update to patch CVE-2024-33186, an authorization bypass vulnerability. The changes are limited to go.mod and go.sum files and correctly reflect the version bump. I have reviewed the changes and found no issues.