CVE-2026-47692: Envoy PROXY Protocol v2 request smuggling via TLV length mismatch

CVE-2026-47692 · Severity: high · CVSS 4.8 · Published 2026-06-26

Envoy is a popular open-source service proxy used to manage network traffic in cloud environments. A flaw in how it handles certain connection headers allows an attacker to 'smuggle' unauthorized data into backend systems, bypassing security filters like authentication or access control. This could allow a high-privileged attacker on the local network to send malicious commands directly to internal applications.

Technologies: Envoy Proxy Envoy, Google Cloud Platform. Vendors: Envoy Proxy, Google.

Quick answers

Is CVE-2026-47692 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-47692 being exploited in the wild.
How severe is CVE-2026-47692?
High severity, with a CVSS score of 4.8, published 26 June 2026.
Which products and versions are affected?
Envoy Proxy Envoy >= 1.34.0, < 1.35.13; >= 1.36.0, < 1.36.9; >= 1.37.0, < 1.37.5; >= 1.38.0, < 1.38.3.
Is there a fix for CVE-2026-47692?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-47692 attacked?
It is attacked from the adjacent network, in a hosted service.
Am I affected by CVE-2026-47692?
Check whether you run Envoy Proxy Envoy or Google Cloud Platform at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A vulnerability exists in Envoy's PROXY Protocol v2 header generation logic within `source/extensions/common/proxy_protocol/proxy_protocol_header.cc`. When the total size of Type-Length-Value (TLV) entries exceeds the 65,535-byte limit, the generator correctly identifies which TLVs to skip but erroneously iterates over the original, unfiltered list when writing to the buffer. This creates a mismatch where the header's length field reflects the filtered size while the actual buffer contains the 'skipped' data. An attacker with high privileges on an adjacent network can exploit this to inject up to 65KB of controlled data into the upstream connection, bypassing L7 filters such as RBAC, JWT, or ext_authz. The issue is fixed in versions 1.35.13, 1.36.9, 1.37.5, and 1.38.3.

Affected products

  • Envoy Proxy Envoy >= 1.34.0, < 1.35.13; >= 1.36.0, < 1.36.9; >= 1.37.0, < 1.37.5; >= 1.38.0, < 1.38.3

Timeline

  • 2026-06-23: advisory: GitHub Security Advisory published
  • 2026-06-26: disclosed: CVE published to NVD

References

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