What’s Vulnerable › Vulnerabilities

CVE-2021-22538: Privilege escalation in RBAC system

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-03-31 · updated 2026-06-17
• Weakness: CWE-20

Description

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.

Affected products

• Google LLC Exposure Notifications Verification Server: before 0.23.1 — fixed in 0.23.1

How to fix

Upgrade to a fixed version: Google LLC Exposure Notifications Verification Server 0.23.1. Check the vendor advisory for mitigations.

References

• https://github.com/google/exposure-notifications-verification-server/commit/eb8cf40b12dbe79304f1133c06fb73419383cd95
• 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
• 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

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