{"cve":"CVE-2026-84303","nvd":{"published":"2026-09-01T19:17:30.600","modified":"2026-09-09T21:09:13.080","status":"Deferred","description":"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.","cvss_v4":{"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N","score":6.3},"cvss_v3":null,"cwes":["CWE-178","CWE-863"],"references":["https://github.com/grpc/grpc-go/commit/db9482836c298f234c896cf82ab68cafc78237f8","https://github.com/grpc/grpc-go/commit/ebba6f3f1b206e2b4dc4d1d5a96d18430302c2fe","https://github.com/grpc/grpc-go/pull/9332","https://github.com/grpc/grpc-go/pull/9335","https://github.com/grpc/grpc-go/releases/tag/v1.83.1"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:50:50.842544443+00:00"},"epss":{"cve":"CVE-2026-84303","score":0.00311,"percentile":0.23996,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-qc2q-p7wx-3px3","url":"https://osv.dev/vulnerability/GHSA-qc2q-p7wx-3px3","summary":"gRPC-Go: xDS RBAC HTTP Filter bypass via mixed-case Header Matching and gRFC A41 validation evasion","modified":"2026-09-15T19:10:32.558419529Z","packages":[{"ecosystem":"Go","name":"google.golang.org/grpc","purl":"pkg:golang/google.golang.org/grpc","ranges":["<1.83.1"],"fixed":["1.83.1"]}]},{"id":"GO-2026-6441","url":"https://osv.dev/vulnerability/GO-2026-6441","summary":"Bypass of xDS RBAC HTTP filter header matching in google.golang.org/grpc","modified":"2026-09-15T19:00:17.130575881Z","packages":[{"ecosystem":"Go","name":"google.golang.org/grpc","purl":"pkg:golang/google.golang.org/grpc","ranges":["<1.83.1"],"fixed":["1.83.1"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}