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High

Security advisory

Type: advisorySources: OSVCVE: CVE-2021-22538

A privilege escalation vulnerability impacting the Google Exposure Notification Verification Server (versions prior to 0.23.1), allows an attacker who (1) has UserWrite permissions and (2) is using a carefully crafted request or malicious proxy, to create another user with higher privileges than their own. This occurs due to insufficient checks on the allowed set of permissions. The new user creation event would be captured in the Event Log.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2021-22538
Confirmed fixed CVEs
Not specified
Updated in this feed
31 Oct 2026, 11:14 UTC · Revision 1

Source evidence

CVE-2021-22538

core-osv · Original source

Published 31 Mar 2021, 21:15 UTC

A privilege escalation vulnerability impacting the Google Exposure Notification Verification Server (versions prior to 0.23.1), allows an attacker who (1) has UserWrite permissions and (2) is using a carefully crafted request or malicious proxy, to create another user with higher privileges than their own. This occurs due to insufficient checks on the allowed set of permissions. The new user creation event would be captured in the Event Log.

osv:CVE-2021-22538
Complete source record
{
  "id": "801c3e7b0a8dcb5db7ccce8f5836186d309544a2e2098c735849aaf3aba702e2",
  "url": "https://osv.dev/vulnerability/CVE-2021-22538",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2021-22538",
    "summary": "A privilege escalation vulnerability impacting the Google Exposure Notification Verification Server (versions prior to 0.23.1), allows an attacker who (1) has UserWrite permissions and (2) is using a carefully crafted request or malicious proxy, to create another user with higher privileges than their own. This occurs due to insufficient checks on the allowed set of permissions. The new user creation event would be captured in the Event Log.",
    "evidence": "osv:CVE-2021-22538",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2021-22538",
      "aliases": [
        "CVE-2021-22538",
        "GHSA-5v95-v8c8-3rh6",
        "GO-2022-0798"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/google/exposure-notifications-verification-server",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "586cc1d38ce3b88034e688b894cda0a6ddc1d278"
                },
                {
                  "fixed": "eb8cf40b12dbe79304f1133c06fb73419383cd95"
                },
                {
                  "fixed": "c1e4d0b5db469cb27cd2be0bffe6ad52cb1b4b56"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:google:exposure_notifications_verification_server:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "0.23.1"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "eb8cf40b12dbe79304f1133c06fb73419383cd95"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "586cc1d38ce3b88034e688b894cda0a6ddc1d278"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v0.23.1"
                  },
                  {
                    "range": [
                      {
                        "fixed": "c1e4d0b5db469cb27cd2be0bffe6ad52cb1b4b56"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v0.24.0"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v0.23.0",
            "v0.22.2",
            "v0.22.1",
            "v0.22.0",
            "v0.21.2",
            "v0.21.1",
            "v0.21.0",
            "v0.20.0",
            "v0.19.2",
            "v0.19.1",
            "v0.18.1",
            "v0.18.0",
            "v0.17.1",
            "v0.17.0",
            "v0.16.0",
            "v0.15.1",
            "v0.15.0",
            "v0.14.0",
            "v0.13.0",
            "v0.12.1",
            "v0.12.0",
            "v0.11.1",
            "v0.11.0",
            "v0.9.0",
            "v0.8.0",
            "v0.7.0",
            "v0.6.0",
            "v0.5.1",
            "v0.5.0",
            "v0.4.0",
            "v0.3.0",
            "v0.2.0",
            "v0.1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-22538.json"
          }
        }
      ],
      "modified": "2026-10-20T10:53:36.496829475Z",
      "provider": "osv",
      "references": [
        "https://github.com/google/exposure-notifications-verification-server/releases/tag/v0.23.1",
        "https://github.com/google/exposure-notifications-verification-server/releases/tag/v0.24.0",
        "https://github.com/google/exposure-notifications-verification-server/security/advisories/GHSA-5v95-v8c8-3rh6",
        "https://github.com/google/exposure-notifications-verification-server/commit/eb8cf40b12dbe79304f1133c06fb73419383cd95"
      ],
      "provider_metadata": {}
    },
    "related_cves": [
      {
        "value": "CVE-2021-22538",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 384436,
  "published_at": "2021-03-31T21:15:16.057+00:00"
}