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Advisory record · GHSA-g53w-w6mj-hrpp

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

CVSS 4.0, no score published

Published by the GitHub Advisory Database at 19 May 2026, 19:42 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
github.com/Kuadrant/mcp-gatewayGo<0.7.00.7.0
Identifiers
GHSA-g53w-w6mj-hrpp · GO-2026-5390
Weakness (CWE)
CWE-287 · CWE-346 · CWE-639
Tags
Published
19 May 2026
Updated
21 Jul 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

MCP Gateway (github.com/Kuadrant/mcp-gateway) versions before 0.7.0 are affected. A caller who can reach the router can send a request carrying a header that bypasses the gateway JWT session check and sets the upstream :authority header to a chosen value. The check depends on a shared router key that is a hardcoded fallback default and, in controller-managed deployments, a value derived from a non-secret resource UID, so the attacker can reach any backend registered with the gateway. Upgrade to version 0.7.0 or later.

Written 6 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
Not published None 4.0 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N GitHub Advisory Database
  • CISA KEV Not listed.
  • EPSS No score.

Timeline

  1. 31 Oct 2026, 15:05 UTC First seen by agentprime
  2. 31 Oct 2026, 15:05 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.