CVE-2026-84303 (GCVE-0-2026-84303)
Vulnerability from cvelistv5
Published
2026-09-01 18:14
Modified
2026-09-02 19:14
Severity ?
6.3 (Medium) - 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
CWE
  • CWE-178 - Improper Handling of Case Sensitivity
  • CWE-863 - Incorrect Authorization
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.
References
Impacted products
Vendor Product Version
grpc grpc-go Version: < 1.83.1
 Create a notification for this product.
Show details on NVD website

To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-84303",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-09-02T19:14:42.460152Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-09-02T19:14:49.353Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "grpc-go",
          "vendor": "grpc",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.83.1"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 6.3,
            "baseSeverity": "MEDIUM",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "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",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "LOW",
            "vulnIntegrityImpact": "LOW"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-178",
              "description": "CWE-178: Improper Handling of Case Sensitivity",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-863",
              "description": "CWE-863: Incorrect Authorization",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-01T18:14:37.870Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/grpc/grpc-go/security/advisories/GHSA-qc2q-p7wx-3px3",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/grpc/grpc-go/security/advisories/GHSA-qc2q-p7wx-3px3"
        },
        {
          "name": "https://github.com/grpc/grpc-go/pull/9332",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/grpc/grpc-go/pull/9332"
        },
        {
          "name": "https://github.com/grpc/grpc-go/pull/9335",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/grpc/grpc-go/pull/9335"
        },
        {
          "name": "https://github.com/grpc/grpc-go/commit/db9482836c298f234c896cf82ab68cafc78237f8",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/grpc/grpc-go/commit/db9482836c298f234c896cf82ab68cafc78237f8"
        },
        {
          "name": "https://github.com/grpc/grpc-go/commit/ebba6f3f1b206e2b4dc4d1d5a96d18430302c2fe",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/grpc/grpc-go/commit/ebba6f3f1b206e2b4dc4d1d5a96d18430302c2fe"
        },
        {
          "name": "https://github.com/grpc/grpc-go/releases/tag/v1.83.1",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/grpc/grpc-go/releases/tag/v1.83.1"
        }
      ],
      "source": {
        "advisory": "GHSA-qc2q-p7wx-3px3",
        "discovery": "UNKNOWN"
      },
      "title": "gRPC-Go: xDS RBAC HTTP Filter bypass via mixed-case Header Matching and gRFC A41 validation evasion"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-84303",
    "datePublished": "2026-09-01T18:14:37.870Z",
    "dateReserved": "2026-09-01T16:17:43.078Z",
    "dateUpdated": "2026-09-02T19:14:49.353Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.