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VulnerabilityPublished Updated

CVE-2026-42580: netty · HTTP Request/Response Smuggling

Affects nettySource GCVE Database

0

Not known to be exploited · CVSS 6.5 Medium : upgrade to 4.2.13.Final or 4.1.133.Final when convenient.

Data as of 26 Oct 2026, 18:27 UTC

CVSS 3.1 base score
6.5Medium
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 4.2.13.Final, 4.1.133.Final
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 13 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade netty to 4.2.13.Final or 4.1.133.Final.

Affected software

ProductAffectedFixed in
netty nettyAffected
  • >=4.2.0.Alpha1 <4.2.13.Final
  • <4.1.133.Final
Fixed in
  • 4.2.13.Final
  • 4.1.133.Final

AI-suggested

Upgrade Netty to version 4.2.13.Final or later, or 4.1.133.Final or later, where this vulnerability has been fixed. No other mitigation is indicated by the vendor advisory.

Description

CVE-2026-42580 is a medium severity vulnerability in Netty, an asynchronous network application framework. The issue involves an integer overflow in the chunk size parser prior to versions 4.2.13.Final and 4.1.133.Final, which enables HTTP request/response smuggling attacks. This vulnerability has been fixed in the specified versions.

References

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