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HTTP Request Smuggling in Netty

High severity GitHub Reviewed Published Oct 11, 2019 to the GitHub Advisory Database • Updated Jun 29, 2026

Package

maven io.netty:netty (Maven)

Affected versions

>= 3.3.0.Final, <= 4.0.0.Alpha8

Patched versions

None
maven io.netty:netty-all (Maven)
>= 4.0.0.Beta1, < 4.1.42.Final
4.1.42.Final
maven org.jboss.netty:netty (Maven)
<= 3.2.9.Final
None

Description

Netty before 4.1.42.Final mishandles whitespace before the colon in HTTP headers (such as a "Transfer-Encoding : chunked" line), which leads to HTTP request smuggling.

References

Published by the National Vulnerability Database Sep 26, 2019
Reviewed Sep 30, 2019
Published to the GitHub Advisory Database Oct 11, 2019
Last updated Jun 29, 2026

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(94th percentile)

Weaknesses

Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination. Learn more on MITRE.

CVE ID

CVE-2019-16869

GHSA ID

GHSA-p979-4mfw-53vg

Source code

Credits

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