CVE-2026-48743Public exploitNetwork attack vectorHinoki check available

Policy bypass via HTTP request desynchronization

Published Jun 26, 2026 · Updated Jun 26, 2026

HTTP request smuggling in affected Envoy releases allows remote attackers to bypass proxy routing policy via headers-only HTTP/3 streams. Envoy marks a headers-only stream complete but forwards its nonzero Content-Length to HTTP/1, allowing the next request's bytes to satisfy that body and leave a backend-parsed request. Exploitation requires downstream HTTP/3, an early-responding HTTP/1 origin, and upstream connection reuse; the demonstrated result is access to an Envoy-denied route.

CVSS severity7.5
High
EPSS probability0.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

HTTP request smuggling in affected Envoy releases allows remote attackers to bypass proxy routing policy via headers-only HTTP/3 streams. Envoy marks a headers-only stream complete but forwards its nonzero Content-Length to HTTP/1, allowing the next request's bytes to satisfy that body and leave a backend-parsed request. Exploitation requires downstream HTTP/3, an early-responding HTTP/1 origin, and upstream connection reuse; the demonstrated result is access to an Envoy-denied route.

The record

CVE
CVE-2026-48743
Published
Jun 26, 2026
Updated
Jun 26, 2026
Vendor
Envoy Proxy
Product
Envoy
Classifications
CWE-444, CAPEC-33, T1190
Attack vector
network
Privileges
unauthenticated

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=>= 1.35.0, < 1.35.11
  2. Affected versionversion=>= 1.36.0, < 1.36.7
  3. Affected versionversion=>= 1.37.0, < 1.37.3
  4. Affected versionversion=>= 1.38.0, < 1.38.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Envoy Proxy · Envoyversion=>= 1.35.0, < 1.35.11; version=>= 1.36.0, < 1.36.7; version=>= 1.37.0, < 1.37.3; version=>= 1.38.0, < 1.38.1

Published CVSS scores

7.5GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
CAPEC-33HTTP Request Smuggling
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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