High 7.5Published Jul 29, 2026

CVE-2026-59898Netty is an asynchronous, event-driven network application framework.

Updated under an hour ago (2026-10-19 05:50 UTC)

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No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

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.

CVSS: 7.5 HIGH (v3.1, NVD)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Weakness (CWE): CWE-444
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Not given
NVD analysis: Analyzed
Record last updated: Aug 6, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

netty netty netty:netty	before 4.1.136; from 4.2.0 before 4.2.16	NVD

References

https://github.com/netty/netty/releases/tag/netty-4.1.136.Finalrelease-notes
https://github.com/netty/netty/releases/tag/netty-4.2.16.Finalrelease-notes
https://github.com/netty/netty/security/advisories/GHSA-4mp9-239f-g9hgvendor-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.