CVE-2026-84303
gRPC-Go: xDS RBAC HTTP Filter bypass via mixed-case Header Matching and gRFC A41 validation evasion
CVSS Score
0.0
EPSS Score
0.0%
EPSS Percentile
0th
gRPC-Go is the Go language implementation of gRPC. Prior to 1.83.1, the xDS RBAC HTTP filter in internal/xds/httpfilter/rbac/rbac.go does not lowercase header matcher names in normalizeHeaderMatcher even though incoming metadata keys are lowercase. A DENY policy using a mixed-case name such as X-Role or User-Agent therefore does not match and fails open, allowing requests that should be rejected. The same case mismatch permits :Scheme or Grpc-Status to evade gRFC A41 validation and prevents Host from being rewritten to :authority. This issue is fixed in version 1.83.1.
| CWE | CWE-178 CWE-863 |
| Vendor | grpc |
| Product | grpc-go |
| Published | Sep 1, 2026 |
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Affected Versions
grpc / grpc-go
< 1.83.1
References
github.com: https://github.com/grpc/grpc-go/security/advisories/GHSA-qc2q-p7wx-3px3 github.com: https://github.com/grpc/grpc-go/pull/9332 github.com: https://github.com/grpc/grpc-go/pull/9335 github.com: https://github.com/grpc/grpc-go/commit/db9482836c298f234c896cf82ab68cafc78237f8 github.com: https://github.com/grpc/grpc-go/commit/ebba6f3f1b206e2b4dc4d1d5a96d18430302c2fe github.com: https://github.com/grpc/grpc-go/releases/tag/v1.83.1