CVE-2026-42581

Low

No strong exploitation signal.

CVSS base

5.8 MEDIUM

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

EPSS — probability of exploitation (30 days)

0.6%

48.8th percentile

CISA KEV

Not listed

Weakness / dates

CWE-444

Published 2026-05-13 · modified 2026-09-18

CVSS breakdown

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

Attack Vector	N	Network
Attack Complexity	L	Low
Privileges Required	N	None
User Interaction	N	None
Scope	C	Changed
Confidentiality	N	None
Integrity	L	Low
Availability	N	None

Timeline

2026-05-13 — Published (NVD)
2026-09-18 — Last modified (NVD)

Description

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.

Affected

netty

References

Official: NVD · CVE.org