CVE-2026-42580

Netty: HTTP Request Smuggling due to incorrect chunk size parsing

MEDIUM

6.5

CVSS Score

Published: May 13, 2026 at 06:04 PM UTC

Updated: October 26, 2026 at 05:10 PM UTC

2 products affected across 2 vendorsNettyNetty

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Severity

MEDIUM6.5

Exploit prediction

EPSS 0.4%

SSVC

PoC

Description

Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, Netty's chunk size parser silently overflows int, enabling request smuggling attacks. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Netty · Nettymaven

95%

v < 4.1.1334.2.0 ≤ v < 4.2.13

Affected range stops below 4.1.133.Final, so it looks safe — our inference, not a vendor statement

Affected range stops below 4.2.13.Final, so it looks safe — our inference, not a vendor statement

Netty · Io Netty

90%

v < 4.1.133.Final4.2.0.Alpha1 ≤ v < 4.2.13.Final

Affected range stops below 4.1.133.Final, so it looks safe — our inference, not a vendor statement

Affected range stops below 4.2.13.Final, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

https://github.com/netty/netty/security/advisories/GHSA-m4cv-j2px-7723

References (1)

x_refsource_CONFIRMExploitVendor Advisory

Source: cverecord

https://github.com/netty/netty/security/advisories/GHSA-m4cv-j2px-7723

SSVC — Action Prioritization

SSVCPoCAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.5MEDIUMGitHub_M

Attack Vector: NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: NONE
Integrity: LOW
Availability: LOW

Vector?

Quick Info

StatusANALYZED

CWE

CWE-444CWE-190

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