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© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2026-42581

40
FAUCET Score

Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, HttpObjectDecoder strips a conflicting Content-Length header when a request carries both Transfer-Encoding: chunked and Content-Length, but only for HTTP/1.1 messages. The guard is absent for HTTP/1.0. An attacker that sends an HTTP/1.0 request with both headers causes Netty to decode the body as chunked while leaving Content-Length intact in the forwarded HttpMessage. Any downstream proxy or handler that trusts Content-Length over Transfer-Encoding will disagree on message boundaries, enabling request smuggling. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.

First published: May 13, 2026Last modified: May 13, 2026

Impacted Technologies

VendorProductVersion(s)CPE
< 4.1.133CPE matchmatch criteria
cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*
>= 4.2.0, < 4.2.13CPE matchmatch criteria
cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.8MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
NONE
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
1.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.61%
Probability of exploitation in next 30 days
EPSS Percentile
45.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0061 is in the 26th percentile among its peer group of 36,897 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (10)

mavenpatch availablevia ghsa
Product: io.netty:netty-codec-httpFixed in: 4.2.13.Final
mavenpatch availablevia ghsa
Product: io.netty:netty-codec-httpFixed in: 4.1.133.Final
ubuntupatch availablevia ubuntu_usn
Product: netty (bionic)Fixed in: 1:4.1.7-4ubuntu0.1+esm6
ubuntupatch availablevia ubuntu_usn
Product: netty (focal)Fixed in: 1:4.1.45-1ubuntu0.1~esm6
ubuntupatch availablevia ubuntu_usn
Product: netty (jammy)Fixed in: 1:4.1.48-4+deb11u2ubuntu0.1+esm3
ubuntupatch availablevia ubuntu_usn
Product: netty (noble)Fixed in: 1:4.1.48-9ubuntu0.1+esm3
ubuntupatch availablevia ubuntu_usn
Product: netty (resolute)Fixed in: 1:4.1.48-16ubuntu0.1~esm2
ubuntupatch availablevia ubuntu_usn
Product: netty (trusty)Fixed in: 1:3.2.6.Final-2+deb8u2ubuntu0.1~esm1
ubuntupatch availablevia ubuntu_usn
Product: netty (xenial)Fixed in: 1:4.0.34-1ubuntu0.1~esm4
github_advisoryworkaround availablevia nvd_reference
View patch

Vendor Advisories (2)

ubuntuUSN-8401-1

Netty vulnerabilities

Jun 8, 2026
mavenGHSA-xxqh-mfjm-7mv9medium

Netty HTTP/1.0 TE+CL Coexistence Bypasses Smuggling Sanitization

May 7, 2026

References

access.redhat.com / errata/RHSA-2026:23808
access.redhat.com / errata/RHSA-2026:24502
access.redhat.com / errata/RHSA-2026:25123
access.redhat.com / errata/RHSA-2026:28010
access.redhat.com / errata/RHSA-2026:36820
access.redhat.com / errata/RHSA-2026:37390
access.redhat.com / errata/RHSA-2026:42644
access.redhat.com / security/cve/CVE-2026-42581
bugzilla.redhat.com / show_bug.cgi
security.access.redhat.com / data/csaf/v2/vex/2026/cve-2026-42581.json
github.com / netty/netty/security/advisories/GHSA-xxqh-mfjm-7mv9
ExploitMitigationVendor Advisory