Is CVE-2026-42580 in the CISA KEV catalog?

No. CVE-2026-42580 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-42580?

CVE-2026-42580 has a CVSS v3 base score of 6.5 (MEDIUM).

What is the EPSS score for CVE-2026-42580?

CVE-2026-42580 has an EPSS score of 0.36% (28th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-42580?

Upgrade netty to 4.2.13 or later.

CVE & CISA-KEV Catalog

CVE-2026-42580

MEDIUM

6.5

CVSS v3

NVD

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.

CWE-190Integer Overflow CWE-444

How to fix

Remediation Available

nettyNVD

Affected:>= 4.2.0, < 4.2.13Fixed in:4.2.13CVE-2026-42580derived from NVD

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

IntegrityLow

AvailabilityLow

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

Exploit Intelligence

0.36%probability of exploitation in 30 days

28thpercentile

Low risk: more likely to be exploited than 28% of all known CVEs.

References

Exploit1

github.com

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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 2026-05-18.