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Fencer Intel
medium 6.3

CVE-2026-84303 json

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

published 2mo ago modified last mo. also EUVD-2026-69419 , GHSA-qc2q-p7wx-3px3 , GO-2026-6441

cvss
6.3
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 24%
public exploits
0
none known

Summary

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.

Patch / fix

  • go google.golang.org/grpc 1.83.1
  • grpc grpc 1.83.1
  • kubevirt SLE Module for Containers 15 SP7 1.7.4-150700.3.42.1
  • terraform-provider-aws SLE Module for Public Cloud 15 SP5, SLE Module for Public Cloud 15 SP4 3.11.0-150200.6.29.2
  • terraform-provider-tls SLE Module for Public Cloud 15 SP5, SLE Module for Public Cloud 15 SP4 3.0.0-150200.5.26.2
  • terraform-provider-helm SLE Module for Public Cloud 15 SP5, SLE Module for Public Cloud 15 SP4 2.9.0-150200.6.34.2
  • terraform-provider-null SLE Module for Public Cloud 15 SP5, SLE Module for Public Cloud 15 SP4 3.0.0-150200.6.32.2
  • terraform-provider-local SLE Module for Public Cloud 15 SP5, SLE Module for Public Cloud 15 SP4 2.0.0-150200.6.30.2
  • terraform-provider-google SLE Module for Public Cloud 15 SP5, SLE Module for Public Cloud 15 SP4 3.43.0-150200.6.23.2
  • terraform-provider-random SLE Module for Public Cloud 15 SP5, SLE Module for Public Cloud 15 SP4 3.0.0-150200.6.26.2

suse advisories SUSE-SU-2026:5167-1SUSE-SU-2026:4628-1SUSE-SU-2026:24150-1SUSE-SU-2026:4444-1SUSE-SU-2026:4389-1SUSE-SU-2026:4388-1

  • rqlite openSUSE Leap 16.0 10.6.6-bp160.1.1
  • warewulf4 openSUSE Leap 16.0 4.7.1-bp160.2.1
  • warewulf4 openSUSE Tumbleweed 4.7.1-2.1
  • kubevirt1.8 openSUSE Tumbleweed 1.8.4-7.1
  • gh openSUSE Leap 16.0 2.102.0-bp160.1.1
  • alloy openSUSE Tumbleweed 1.20.1-1.1
  • amazon-ecs-init openSUSE Leap 16.0 1.107.0-160000.1.1
  • grafana openSUSE Tumbleweed 12.4.11-1.1

opensuse advisories openSUSE-SU-2026:22224-1openSUSE-SU-2026:22221-1openSUSE-SU-2026:12375-1openSUSE-SU-2026:12241-1openSUSE-SU-2026:22134-1openSUSE-SU-2026:12114-1

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-84303 updated cvss 6.5

github.com/grpc/grpc-go: gRPC-Go: RBAC policy bypass and validation evasion via mixed-case header matching

  • Red Hat OpenShift AI (RHOAI) rhoai/odh-mlflow-operator-rhel9, rhoai/odh-mod-arch-gen-ai-rhel9, rhoai/odh-workbenches-operator-rhel9, rhoai/odh-model-registry-operator-rhel9, rhoai/odh-kuberay-operator-controller-rhel9
    affected: no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
2mo ago

Exploit prediction

0.31% chance of exploitation in the next 30 days, higher than 24% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 4.0 6.3 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
CNA 4.0 6.3 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

Affected packages

ecosystem package affected fixed in
go google.golang.org/grpc
<1.83.1
1.83.1

Affected products

  • grpc grpc-go

Classification

Weakness
  • CWE-178 Improper Handling of Case Sensitivity
  • CWE-863 Incorrect Authorization

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.