{"id":"UBUNTU-CVE-2026-84303","details":"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.","modified":"2026-09-16T14:02:37.920801316Z","published":"2026-09-01T19:17:00Z","upstream":["CVE-2026-84303"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-84303"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-84303"},{"type":"REPORT","url":"https://github.com/grpc/grpc-go/security/advisories/GHSA-qc2q-p7wx-3px3"},{"type":"REPORT","url":"https://github.com/grpc/grpc-go/pull/9332"},{"type":"REPORT","url":"https://github.com/grpc/grpc-go/pull/9335"}],"affected":[{"package":{"name":"golang-google-grpc","ecosystem":"Ubuntu:16.04:LTS","purl":"pkg:deb/ubuntu/golang-google-grpc?arch=source&distro=xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.0~git20150514.0.f5ebd86-1","0.0~git20150514.0.f5ebd86-2","0.0~git20151002.0.3e7b7e5-1"],"ecosystem_specific":{"binaries":[{"binary_name":"golang-google-grpc-dev","binary_version":"0.0~git20151002.0.3e7b7e5-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-84303.json"}},{"package":{"name":"google-guest-agent","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/google-guest-agent?arch=source&distro=esm-apps-legacy%2Fxenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["20201217.02-0ubuntu1~16.04.0","20230426.00-0ubuntu2~16.04.3","20231004.02-0ubuntu1~16.04.1","20231004.02-0ubuntu1~16.04.2","20240716.00-0ubuntu1~16.04.0","20240716.00-0ubuntu1~16.04.0+esm1","20240716.00-0ubuntu1~16.04.0+esm2","20240716.00-0ubuntu1~16.04.0+esm3"],"ecosystem_specific":{"binaries":[{"binary_version":"20240716.00-0ubuntu1~16.04.0+esm3","binary_name":"google-guest-agent"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-84303.json"}},{"package":{"name":"grpc","ecosystem":"Ubuntu:16.04:LTS","purl":"pkg:deb/ubuntu/grpc?arch=source&distro=xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.10.2-1","0.11.1-1"],"ecosystem_specific":{"binaries":[{"binary_version":"0.11.1-1","binary_name":"libgrpc0"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-84303.json"}},{"package":{"name":"golang-google-grpc","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/golang-google-grpc?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.0.4-1","1.6.0-2","1.6.0-3","1.6.0-3ubuntu0.18.04.1"],"ecosystem_specific":{"binaries":[{"binary_name":"golang-google-grpc-dev","binary_version":"1.6.0-3ubuntu0.18.04.1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-84303.json"}},{"package":{"name":"google-guest-agent","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/google-guest-agent?arch=source&distro=esm-apps%2Fbionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["20201217.02-0ubuntu1~18.04.0","20210414.00-0ubuntu1~18.04.0","20210629.00-0ubuntu1~18.04.1","20220622.00-0ubuntu2~18.04.0","20220622.00-0ubuntu2~18.04.1","20230426.00-0ubuntu2~18.04.0","20231004.02-0ubuntu1~18.04.2","20231004.02-0ubuntu1~18.04.3","20240716.00-0ubuntu1~18.04.0","20241011.01-0ubuntu1~18.04.0","20241011.01-0ubuntu1~18.04.0+esm1","20241011.01-0ubuntu1~18.04.0+esm2","20241011.01-0ubuntu1~18.04.0+esm3"],"ecosystem_specific":{"binaries":[{"binary_name":"google-guest-agent","binary_version":"20241011.01-0ubuntu1~18.04.0+esm3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-84303.json"}},{"package":{"name":"grpc","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/grpc?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.2-1","1.3.2-1ubuntu1","1.3.2-1.1~build1"],"ecosystem_specific":{"binaries":[{"binary_version":"1.3.2-1.1~build1","binary_name":"libgrpc++1"},{"binary_name":"libgrpc3","binary_version":"1.3.2-1.1~build1"},{"binary_version":"1.3.2-1.1~build1","binary_name":"protobuf-compiler-grpc"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-84303.json"}},{"package":{"name":"google-guest-agent","ecosystem":"Ubuntu:Pro:20.04:LTS","purl":"pkg:deb/ubuntu/google-guest-agent?arch=source&distro=esm-infra%2Ffocal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["20201217.02-0ubuntu1~20.04.0","20210414.00-0ubuntu1~20.04.0","20210629.00-0ubuntu1~20.04.0","20220622.00-0ubuntu2~20.04.0","20220622.00-0ubuntu2~20.04.2","20230426.00-0ubuntu2~20.04.0","20231004.02-0ubuntu1~20.04.1","20231004.02-0ubuntu1~20.04.2","20231004.02-0ubuntu1~20.04.3","20231004.02-0ubuntu1~20.04.4","20240716.00-0ubuntu1~20.04.0","20241011.01-0ubuntu1~20.04.1","20250116.00-0ubuntu1~20.04.0","20250116.00-0ubuntu1~20.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