gRPC-Go: xDS RBAC HTTP Filter bypass via mixed-case Header Matching and gRFC A41 validation evasion

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-84303
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-01 19:17:30 UTC
Updated2026-09-02 20:17:39 UTC
DescriptiongRPC-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.

Risk And Classification

Primary CVSS: v4.0 6.3 MEDIUM from [email protected]

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS: 0.003110000 probability, percentile 0.233880000 (date 2026-09-02)

Problem Types: CWE-178 | CWE-863 | CWE-178 CWE-178: Improper Handling of Case Sensitivity | CWE-863 CWE-863: Incorrect Authorization

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary6.3MEDIUMCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/C...
4.0CNADECLARED6.3MEDIUMCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
Present
Privileges Required
None
User Interaction
None
Confidentiality
Low
Integrity
Low
Availability
None
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Grpc Grpc-go affected < 1.83.1 Not specified

References

ReferenceSourceLinkTags
github.com/grpc/grpc-go/commit/db9482836c298f234c896cf82ab68cafc78237f8 [email protected] github.com
github.com/grpc/grpc-go/pull/9335 [email protected] github.com
github.com/grpc/grpc-go/security/advisories/GHSA-qc2q-p7wx-3px3 [email protected] github.com
github.com/grpc/grpc-go/commit/ebba6f3f1b206e2b4dc4d1d5a96d18430302c2fe [email protected] github.com
github.com/grpc/grpc-go/releases/tag/v1.83.1 [email protected] github.com
github.com/grpc/grpc-go/pull/9332 [email protected] github.com
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