What is CVE-2026-42580?

CVE-2026-42580 is a medium-severity vulnerability in Io.netty Netty-codec-http, classified under Integer Overflow or Wraparound. CVSS score: 6.5/10. Published 2026-05-13.

How severe is CVE-2026-42580?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Integer overflow in Io.netty Netty-codec-http

CVE-2026-42580

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.Fina…

Vulnerability class: Integer Overflow

EPSS: 0.000 (4.1th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L.

Affected products

Io.netty Netty-codec-http — versions >= 4.2.0.Alpha1, < 4.2.13.Final, < 4.1.133.Final
Netty — versions >= 4.2.0.Alpha1, < 4.2.13.Final, < 4.1.133.Final

Weakness classification (CWE)

References

security-advisories@github.com (x_refsource_CONFIRM, Exploit, Vendor Advisory)

Frequently asked questions

What is CVE-2026-42580?: CVE-2026-42580 is a medium-severity vulnerability in Io.netty Netty-codec-http, classified under Integer Overflow or Wraparound. CVSS score: 6.5/10. Published 2026-05-13.
How severe is CVE-2026-42580?: Medium severity. CVSS v3 base score is 6.5 out of 10.