Incorrect Authorization Affecting github.com/grpc-ecosystem/grpc-gateway/v2/runtime package, versions >=0.0.0
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Start learning- Snyk IDSNYK-GOLANG-GITHUBCOMGRPCECOSYSTEMGRPCGATEWAYV2RUNTIME-19432132
- published30 Aug 2026
- disclosed28 Aug 2026
- creditMariusz Maik
Introduced: 28 Aug 2026
NewCVE-2026-37236 (opens in a new tab)How to fix?
There is no fixed version for github.com/grpc-ecosystem/grpc-gateway/v2/runtime.
Overview
Affected versions of this package are vulnerable to Incorrect Authorization in the ServeHTTP method of ServeMux (runtime/mux.go), which rewrites r.Method from the client-supplied X-HTTP-Method-Override header on form-urlencoded POST requests without restricting the allowed methods. An attacker can reach handlers for restricted verbs such as DELETE, PUT, or PATCH, bypassing method-based access controls enforced at an upstream proxy or WAF, by sending a POST request with Content-Type: application/x-www-form-urlencoded and the override header set to the target method. This requires a deployment where a perimeter proxy or WAF filters on the wire method while trusting the gateway downstream, and a handler must exist for the overridden method.
Note: The WithDisablePathLengthFallback is added in version 2.29.0 but it is disabled by default.
Workaround
This vulnerability can be avoided by stripping the X-HTTP-Method-Override header at the perimeter proxy or WAF, so the enforced wire method is the one the gateway routes on.