CVE-2026-6338Network attack vector

Backend desynchronization via HTTP parsing flaw

Published Jun 11, 2026 · Updated Jun 11, 2026

HTTP request smuggling in Kong Gateway Enterprise 3.4 and 3.10 through 3.14 allows remote attackers to desynchronize backend traffic. Kong identifies the locus as its HTTP request processing pipeline, which interprets untrusted HTTP/1.1 traffic inconsistently. Reachability requires HTTP/1.1 input and a downstream component that parses the request differently; Kong has not disclosed the exact parser operation.

CVSS severityUnavailable
Unscored
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

HTTP request smuggling in Kong Gateway Enterprise 3.4 and 3.10 through 3.14 allows remote attackers to desynchronize backend traffic. Kong identifies the locus as its HTTP request processing pipeline, which interprets untrusted HTTP/1.1 traffic inconsistently. Reachability requires HTTP/1.1 input and a downstream component that parses the request differently; Kong has not disclosed the exact parser operation.

The record

CVE
CVE-2026-6338
Published
Jun 11, 2026
Updated
Jun 11, 2026
Vendor
Kong Inc.
Product
Kong Gateway Enterprise
Classifications
CWE-444, CAPEC-33, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 11, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=3.10.0.0 <3.10.0.12
  2. Affected versionversion=3.11.0.0 <3.11.0.12
  3. Affected versionversion=3.12.0.0 <3.12.0.7
  4. Affected versionversion=3.13.0.0 <3.13.0.5
  5. Affected versionversion=3.14.0.0 <3.14.0.4
  6. Affected versionversion=3.4.0.0 <3.4.3.27

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Kong Inc. · Kong Gateway Enterpriseversion=3.10.0.0 <3.10.0.12; version=3.11.0.0 <3.11.0.12; version=3.12.0.0 <3.12.0.7; version=3.13.0.0 <3.13.0.5; version=3.14.0.0 <3.14.0.4; version=3.4.0.0 <3.4.3.27

Published CVSS scores

4.9KongCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:P

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
CAPEC-33HTTP Request Smuggling
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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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