CVE catalog

CVE-2026-42581

Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, HttpObjectDecoder strips a conflicting Content-Length header when a request carries both

[CVE catalog]

Severity: High · CVSS 7.3CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Published: May 5, 2026, 10:00:00 PM UTC
Source: [NVD] · [CVE record]
EPSS: 0.63% · Oct 25, 2026

Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, HttpObjectDecoder strips a conflicting Content-Length header when a request carries both Transfer-Encoding: chunked and Content-Length, but only for HTTP/1.1 messages. The guard is absent for HTTP/1.0. An attacker that sends an HTTP/1.0 request with both headers causes Netty to decode the body as chunked while leaving Content-Length intact in the forwarded HttpMessage. Any downstream proxy or handler that trusts Content-Length over Transfer-Encoding will disagree on message boundaries, enabling request smuggling. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.

Vulnerable and fixed packages

Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.

Distribution	Package	Release	Version	Status
Debian	netty	sid	`1:4.1.48-16`	vulnerable
Debian	netty	forky	`1:4.1.48-16`	vulnerable
Debian	netty	trixie	`1:4.1.48-10+deb13u1`	vulnerable
Debian	netty	trixie-security	`1:4.1.48-10+deb13u1`	vulnerable
Debian	netty	bookworm	`1:4.1.48-7+deb12u2`	vulnerable
Debian	netty	bookworm-security	`1:4.1.48-7+deb12u2`	vulnerable
Cpe	netty	Not reported	`1:4.1.48-9ubuntu0.1+esm3`	fixed
Cpe	libnetty-java	Not reported	`1:4.1.48-9ubuntu0.1+esm3`	fixed
Cpe	netty	Not reported	Not reported	vulnerable
Cpe	netty	Not reported	`4.1.133`	fixed
Cpe	netty	Not reported	`4.2.13`	fixed
Cpe	netty	Not reported	`4.2.13`	fixed

Fixed-version evidence

Distribution	Package	Type	Release	Fixed version	Urgency	Origin	Bugs
Debian	netty	source	sid	`(unfixed)`	not yet assigned	Not reported	[1139914]
Debian	netty	source	forky	`(unfixed)`	not yet assigned	Not reported	[1139914]
Debian	netty	source	trixie	`(unfixed)`	not yet assigned	Not reported	[1139914]
Debian	netty	source	bookworm	`(unfixed)`	not yet assigned	Not reported	[1139914]
Cpe	netty	cpe	Not reported	`1:4.1.48-9ubuntu0.1+esm3`	Not reported	Not reported	Not reported
Cpe	libnetty-java	cpe	Not reported	`1:4.1.48-9ubuntu0.1+esm3`	Not reported	Not reported	Not reported
Cpe	netty	cpe	Not reported	`4.1.133`	Not reported	Not reported	Not reported
Cpe	netty	cpe	Not reported	`4.2.13`	Not reported	Not reported	Not reported
Cpe	netty	cpe	Not reported	`4.2.13`	Not reported	NVD-CVE-2026-42581	Not reported

[Debian bug #1139914]

OpenFactory catalog packages

[Debian 12 (Bookworm)]

[libnetty-java]Affected
Source package: [netty]
Details (4)
- 1:4.1.48-7+deb12u2 · all · bookworm
  Affected
  nvd · netty · debian · bookworm; nvd · netty · debian · 12
- 1:4.1.48-7+deb12u2 · all · bookworm
  Affected
  nvd · netty · debian · bookworm; nvd · netty · debian · 12
- 1:4.1.48-7+deb12u2 · all · bookworm-security
  Affected
  nvd · netty · debian · bookworm; nvd · netty · debian · 12
- 1:4.1.48-7+deb12u2 · all · bookworm-security
  Affected
  nvd · netty · debian · bookworm; nvd · netty · debian · 12

[Debian 13 (Trixie)]

[libnetty-java]Affected
Source package: [netty]
Details (4)
- 1:4.1.48-10+deb13u1 · all · trixie
  Affected
  nvd · netty · debian · 13
- 1:4.1.48-10+deb13u1 · all · trixie
  Affected
  nvd · netty · debian · 13
- 1:4.1.48-10+deb13u1 · all · trixie-security
  Affected
  nvd · netty · debian · 13
- 1:4.1.48-10+deb13u1 · all · trixie-security
  Affected
  nvd · netty · debian · 13

Observed: Oct 27, 2026, 7:51:59 AM UTC

References

[CERT-Bund public advisories] · [Debian Security Tracker] · [FIRST EPSS] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX] · [Ubuntu Security Notices (USN)]