CVE-2026-59898

MEDIUM

Netty: WebSockets V07/V08 handshaker missing Connection/Upgrade validation

Title source: cna
STIX 2.1

Description

Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and 4.2.16.Final, ab attacker can force WebSocket upgrade via the lax V07 (or V08) handshaker by sending `Sec-WebSocket-Version: 7` and omitting `Connection: Upgrade` / `Upgrade: websocket` headers, completing a protocol switch that a proxy would not recognize as an Upgrade request and enabling HTTP request smuggling / protocol-confusion attacks. This issue has been fixed in versions 4.1.136.Final and 4.2.16.Final.

References (3)

Core 3

Scores

CVSS v4 6.3
EPSS 0.0027
EPSS Percentile 18.4%
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact partial

Details

CWE
CWE-444
Status published
Products (2)
netty/netty < 4.1.136.Final
netty/netty >=4.2.0.Final, < 4.2.16.Final
Published Jul 29, 2026
Tracked Since Jul 30, 2026