High severity · published May 13, 2026
CVE-2026-42585
Netty: HTTP Request Smuggling due to malformed Transfer-Encoding
7.5
CVSS
0.3%
EPSS
No
On KEV
Description
Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, Netty incorrectly parses malformed Transfer-Encoding, enabling request smuggling attacks. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 19% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
NE
netty · netty
>= 4.2.0.Alpha1, < 4.2.13.Final; < 4.1.133.Final · source: vendor, NVD
NE
netty-codec-http · io.netty
>= 4.2.0.Alpha1, < 4.2.13.Final; < 4.1.133.Final · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-42585
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-42585
Exploit
https://github.com/netty/netty/security/advisories/GHSA-38f8-5428-x5cv
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