GHSA-cqqj-4p63-rrmm CVE-2019-20444

HTTP Request Smuggling in Netty

Critical Maven

Severity: 9.1 / 10; Critical · CVSS 3.1
Exploit chance (EPSS): 8.91%; Chance of exploitation in the next 30 days. Higher than 95.24% of scored vulnerabilities.
Known exploited: No; Not in CISA's catalog
Weakness: CWE-444 Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Fix: 4.1.44; Upgrade io.netty:netty-codec-http to this version or later

Description

HttpObjectDecoder.java in Netty before 4.1.44 allows an HTTP header that lacks a colon, which might be interpreted as a separate header with an incorrect syntax, or might be interpreted as an "invalid fold."

Affected versions

Maven

Package	Vulnerable	Fixed in
io.netty:netty	`all versions`	No fix yet
io.netty:netty-codec-http	`< 4.1.44`	`4.1.44`
org.jboss.netty:netty	`all versions`	No fix yet

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

io.netty:netty-codec-http Maven → `4.1.44`

maven

<dependency><groupId>io.netty</groupId><artifactId>netty-codec-http</artifactId><version>4.1.44</version></dependency>

gradle

implementation("io.netty:netty-codec-http:4.1.44")

Severity breakdown

CVSS 3.1 9.1

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

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

Weakness

CWE-444: 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.

How to prevent it

Implementation: Use a web server that employs a strict HTTP parsing procedure, such as Apache [REF-433].
Implementation: Use only SSL communication.
Implementation: Terminate the client session after each request.
System Configuration: Turn all pages to non-cacheable.

References

Advisories

nvd.nist.gov/vuln/detail/CVE-2019-20444

Packages

github.com/netty/netty

Timeline

Feb 21, 2020 Published
Jul 2, 2025 Last updated by the source
Oct 31, 2026 Latest EPSS score

Advisory	Severity	Why it's related
GHSA-8c42-7qj2-3j46 Netty Vulnerable to Cache Poisoning and Information Disclosure via CORS Vary Header Overwrite	High	Also affects io.netty:netty-codec-http
GHSA-gcjf-9mgh-3p7g Netty: CRLF Injection via Multipart Filename in Netty HttpPostRequestEncoder	Medium	Also affects io.netty:netty-codec-http
GHSA-q4f6-jm68-57ww Netty: [HttpContentEncoder] Unbounded Per-Connection Queue Growth via HTTP/1.1 Pipelining Leads to Denial of Service	High	Also affects io.netty:netty-codec-http
GHSA-4mp9-239f-g9hg Netty: WebSockets V07/V08 handshaker missing Connection/Upgrade validation	High	Also affects io.netty:netty-codec-http
GHSA-6cqp-g7gg-8hr5 Netty: Security Control Bypass via CORS Short-Circuit Failure	Medium	Also affects io.netty:netty-codec-http
GHSA-jppx-w49h-x2qq Netty: [SpdyHttpDecoder] ByteBuf Reference Leak on RST_STREAM Leads to Native Memory Exhaustion	High	Also affects io.netty:netty-codec-http
GHSA-mvh2-crg5-v77c Netty SPDY zlib header block continues decoded expansion after maxHeaderSize truncation	High	Also affects io.netty:netty-codec-http
GHSA-6jqx-86gh-f27w Netty SPDY SETTINGS frame count materializes unbounded settings map	High	Also affects io.netty:netty-codec-http

Is this in your code?

MergeHarbor checks every repository's dependencies against this database, ranks what matters by exploitability and reachability, routes it to the owning team and opens the fix pull request.

Check your repos with MergeHarbor