How severe is GHSA-g53w-w6mj-hrpp?

No CVSS score has been assigned to GHSA-g53w-w6mj-hrpp yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-g53w-w6mj-hrpp?

GHSA-g53w-w6mj-hrpp affects the following packages: github.com/Kuadrant/mcp-gateway (Go). Ecosystems affected: Go.

How do I fix GHSA-g53w-w6mj-hrpp?

Update github.com/Kuadrant/mcp-gateway to 0.7.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-g53w-w6mj-hrpp is resolved across your whole dependency graph.

How do I detect GHSA-g53w-w6mj-hrpp in my Go dependencies?

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

How do I mitigate GHSA-g53w-w6mj-hrpp if there is no patch (or I can't update yet)?

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.

Is GHSA-g53w-w6mj-hrpp actively exploited in the wild?

No public exploit code has been indexed for GHSA-g53w-w6mj-hrpp yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

When was GHSA-g53w-w6mj-hrpp published, and has it been updated?

GHSA-g53w-w6mj-hrpp was published on May 19, 2026 and was last updated on July 21, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹 Go

Not in CISA KEV

GHSA-g53w-w6mj-hrpp — mcp-gateway

Fix: Kuadrant/mcp-gateway@6052079

GHSA-g53w-w6mj-hrpp is a security vulnerability in github.com/Kuadrant/mcp-gateway. A fix is available for github.com/Kuadrant/mcp-gateway — see the affected versions and patch details below.

MCP Gateway: Authority-injection and JWT/session bypass via the unauthenticated router hair-pin "router-key" / "mcp-init-host" path

Also known asGO-2026-5390

Published

May 19, 2026

Updated

Jul 21, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Jul 21, 2026 · OSV.dev, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected

🐹github.com/Kuadrant/mcp-gateway

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

Summary

The MCP router (ext_proc) exposes an initialize-method code path that, when a request carries an mcp-init-host header, bypasses the gateway JWT session validator and rewrites the upstream :authority header to whatever the caller chooses, gated only by a single shared header value (router-key). The shared value is

a literal string (secret-api-key) baked into cmd/mcp-broker-router/main.go as a fall-back default, and
in controller-managed deployments, a SHA-256 truncation of the MCPGatewayExtension UID — a non-secret value visible to anyone with get permission on the resource, and additionally exposed in argv because it is passed to the broker-router container via --mcp-router-key=....

A request that satisfies the trivial header check is forwarded to any backend listener registered with the gateway (including external services such as api.githubcopilot.com when configured), bypassing both the broker (where the signed x-mcp-authorized capability filter is enforced) and the gateway's JWT-based session model.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/Kuadrant/mcp-gateway`	all versions	0.7.0`go get github.com/Kuadrant/mcp-gateway@v0.7.0`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/Kuadrant/mcp-gateway, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/Kuadrant/mcp-gateway to 0.7.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-g53w-w6mj-hrpp 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.

Frequently Asked Questions

## Summary The MCP router (ext_proc) exposes an `initialize`-method code path that, when a request carries an `mcp-init-host` header, bypasses the gateway JWT session validator and rewrites the upstream `:authority` header to whatever the caller chooses, gated only by a single shared header value (`router-key`). The shared value is * a literal string (`secret-api-key`) baked into `cmd/mcp-broker-router/main.go` as a fall-back default, and * in controller-managed deployments, a SHA-256 truncation of the `MCPGatewayExtension` UID — a non-secret value visible to anyone with `get` permiss

O3 Security · Impact-Aware SCA

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