CVE-2026-47692Public exploit

Request smuggling via unfiltered PROXY v2 TLVs

Published Jun 26, 2026 · Updated Jun 26, 2026

Request smuggling in Envoy allows context-dependent attackers to inject bytes into upstream connections via oversized PROXY v2 TLVs. In generateV2Header(), the size field uses filtered final_tlvs, but the emit loop writes unfiltered combined_tlv_vector entries beyond 65,535 bytes. Exploitation requires passthrough TLVs on the listener and upstream cluster plus an added TLV; spillover bypasses Envoy L7 filters.

CVSS severity4.8
Medium
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Request smuggling in Envoy allows context-dependent attackers to inject bytes into upstream connections via oversized PROXY v2 TLVs. In generateV2Header(), the size field uses filtered final_tlvs, but the emit loop writes unfiltered combined_tlv_vector entries beyond 65,535 bytes. Exploitation requires passthrough TLVs on the listener and upstream cluster plus an added TLV; spillover bypasses Envoy L7 filters.

The record

CVE
CVE-2026-47692
Published
Jun 26, 2026
Updated
Jun 26, 2026
Vendor
Envoy Proxy
Product
Envoy
Classifications
CWE-130, T1190
Attack vector
adjacent
Privileges
Unavailable

Timeline

How it unfolded

  1. Jun 26, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 26, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 1.34.0, < 1.35.13
  2. Affected versionversion=>= 1.36.0, < 1.36.9
  3. Affected versionversion=>= 1.37.0, < 1.37.5
  4. Affected versionversion=>= 1.38.0, < 1.38.3

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesUnavailable in this record.

What is affected?

Envoy Proxy · Envoyversion=>= 1.34.0, < 1.35.13; version=>= 1.36.0, < 1.36.9; version=>= 1.37.0, < 1.37.5; version=>= 1.38.0, < 1.38.3

Published CVSS scores

4.8GitHub, Inc.CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:C/C:N/I:L/A:L
4.3NIST NVDCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-130Improper Handling of Length Parameter Inconsistency
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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