CVSS 4.0
6.3 mediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:NCVE-2026-84303
Medium (6.3). EPSS 0.3% chance of exploitation in the next 30 days. Fixed in google.golang.org/grpc 1.83.1.
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.
Severity
- EPSS
- 0.3% chance of exploitation in the next 30 days; higher than 23% of CVEs (scores of 2026-10-31)
- CWEs
- CWE-178, CWE-863
- Published
- Modified
- Record from
- the NVD, synced
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-qc2q-p7wx-3px3 | Go | google.golang.org/grpc | <1.83.1 | 1.83.1 |
| GO-2026-6441 | Go | google.golang.org/grpc | <1.83.1 | 1.83.1 |