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Advisory details: gitlab / maven/io.netty/netty-codec-http/CVE-2026-42581
Advisory ID gitlab/maven/io.netty/netty-codec-http/CVE-2026-42581
Aliases CVE-2026-42581
GHSA-xxqh-mfjm-7mv9
Summary Netty HTTP/1.0 TE+CL Coexistence Bypasses Smuggling Sanitization `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. ---
Status Published
Exploitability 0.5
Weighted Severity 0.0
Risk
Affected and Fixed Packages Package Details
Introduced and Fixed Package Commit Patches Package Commit Patches Details
Weaknesses (3)
CWE-444 Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
CWE-937 OWASP Top Ten 2013 Category A9 - Using Components with Known Vulnerabilities
CWE-1035 OWASP Top Ten 2017 Category A9 - Using Components with Known Vulnerabilities
System Score Found at
cvssv3.1 https://gitlab.com/gitlab-org/advisories-community/-/blob/main/maven/io.netty/netty-codec-http/CVE-2026-42581.yml
Reference id Reference type URL
CVE-2026-42581 https://nvd.nist.gov/vuln/detail/CVE-2026-42581
GHSA-xxqh-mfjm-7mv9 https://github.com/advisories/GHSA-xxqh-mfjm-7mv9
GHSA-xxqh-mfjm-7mv9 Other https://github.com/netty/netty/security/advisories/GHSA-xxqh-mfjm-7mv9
No exploits are available.

No EPSS data available for this advisory.

Patch URL
There are no known patches.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N Found at https://gitlab.com/gitlab-org/advisories-community/-/blob/main/maven/io.netty/netty-codec-http/CVE-2026-42581.yml
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none

Vector: SSVCv2/E:P/A:Y/T:P/P:M/B:A/M:M/D:T/2026-05-13T18:42:38Z/

Decision: Track

Source URL: https://github.com/cisagov/vulnrichment/blob/develop/2026/42xxx/CVE-2026-42581.json

Source Advisory: vulnrichment/CVE-2026-42581

View SSVC decision tree 
[{'Exploitation': 'poc'},
 {'Automatable': 'yes'},
 {'Technical Impact': 'partial'},
 {'Mission Prevalence': 'minimal'},
 {'Public Well-being Impact': 'material'},
 {'Mission & Well-being': 'medium'}]