fix(security/unknown): update module google.golang.org/grpc to v1.79.3 [security] by renovate-sh-app[bot] · Pull Request #313 · grafana-cold-storage/cortex-tools

renovate-sh-app · 2026-03-19T01:04:01Z

This PR contains the following updates:

Package	Change	Age	Confidence
google.golang.org/grpc	`v1.56.3` → `v1.79.3`

gRPC-Go has an authorization bypass via missing leading slash in :path

CVE-2026-33186 / GHSA-p77j-4mvh-x3m3 / GO-2026-4762

More information

Details

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:

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).
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.

Severity

CVSS Score: 9.1 / 10 (Critical)
Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

References

This data is provided by OSV and the GitHub Advisory Database (CC-BY 4.0).

Authorization bypass in gRPC-Go via missing leading slash in :path in google.golang.org/grpc

CVE-2026-33186 / GHSA-p77j-4mvh-x3m3 / GO-2026-4762

More information

Details

Authorization bypass in gRPC-Go via missing leading slash in :path in google.golang.org/grpc

Severity

Unknown

References

https://github.com/grpc/grpc-go/security/advisories/GHSA-p77j-4mvh-x3m3

This data is provided by OSV and the Go Vulnerability Database (CC-BY 4.0).

Release Notes

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

Conversation

renovate-sh-app Bot commented Mar 19, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

gRPC-Go has an authorization bypass via missing leading slash in :path

Details

Impact

Patches

Workarounds

1. Use a Validating Interceptor (Recommended Mitigation)

2. Infrastructure-Level Normalization

3. Policy Hardening

Severity

References

Authorization bypass in gRPC-Go via missing leading slash in :path in google.golang.org/grpc

Details

Severity

References

Release Notes

Configuration

Need help?

Uh oh!

renovate-sh-app Bot commented Mar 19, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

⚠️ Artifact update problem

File name: go.sum

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

1 participant

renovate-sh-app Bot commented Mar 19, 2026 •

edited

Loading

renovate-sh-app Bot commented Mar 19, 2026 •

edited

Loading