CVE-2026-59898

Q: How do I fix CVE-2026-59898?

Upgrade netty to 4.1.136 or later.

Q: Is CVE-2026-59898 being actively exploited?

Not that we know of. CVE-2026-59898 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.25% is the estimated probability that it will be exploited in the next 30 days. That is higher than 16% of all scored CVEs.

Q: How severe is CVE-2026-59898?

CVE-2026-59898 has a CVSS v3 base score of 7.5, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

Q: What does CVE-2026-59898 affect?

Published advisories record a fix for netty (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

HIGH

7.5

CVSS v3

NVD

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.

CWE-444

How to fix

Remediation Available

nettyNVD

Affected:< 4.1.136Fixed in:4.1.136CVE-2026-59898derived from NVD

Affected:>= 4.2.0, < 4.2.16Fixed in:4.2.16CVE-2026-59898derived from NVD

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityHigh

AvailabilityNone

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

Exploit Intelligence

0.25%probability of exploitation in 30 days

16thpercentile

Low risk: more likely to be exploited than 16% of all known CVEs.

References

Vendor Advisory1

github.com

Release Notes2

Related Vulnerabilities

Other CWE-444 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2022-22536	Critical	10.0	98%	KEV	-
CVE-2025-61884	High	7.5	98%	KEV + Ransom	-
CVE-2020-9490	High	7.5	89%	-	Fix
CVE-2023-41265	Critical	9.6	88%	KEV + Ransom	-
CVE-2023-25690	Critical	9.8	85%	-	Fix
CVE-2022-32214	Medium	6.5	81%	-	Fix

Common questions

How do I fix CVE-2026-59898?

Upgrade netty to 4.1.136 or later.

Is CVE-2026-59898 being actively exploited?

Not that we know of. CVE-2026-59898 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.25% is the estimated probability that it will be exploited in the next 30 days. That is higher than 16% of all scored CVEs.

How severe is CVE-2026-59898?

CVE-2026-59898 has a CVSS v3 base score of 7.5, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2026-59898 affect?

Published advisories record a fix for netty (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

Embed a live status badge for CVE-2026-59898

Markdown

[![CVE-2026-59898](https://tridentstack.com/cve/badge/CVE-2026-59898.svg)](https://tridentstack.com/cve/CVE-2026-59898)

HTML

<a href="https://tridentstack.com/cve/CVE-2026-59898"><img src="https://tridentstack.com/cve/badge/CVE-2026-59898.svg" alt="CVE-2026-59898"></a>

Find and fix vulnerabilities across your fleet

TridentStack Control continuously scans your Windows, macOS, and Linux fleet for known vulnerabilities, prioritizes them by severity and active exploitation, and patches them automatically.

See how it works Start freeThis CVE lookup is free and always will be.

This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-08-06.