CVE-2025-58056Public exploitNetwork attack vector

Request smuggling via lone-LF chunk termination

Published Sep 3, 2025 · Updated Sep 5, 2025

HTTP request smuggling in Netty 4.1.124.Final and earlier and 4.2.0.Alpha3 through 4.2.4.Final allows remote attackers to bypass access controls. HttpObjectDecoder treats a lone LF in an HTTP/1.1 chunk extension as the end of the chunk-size line instead of requiring CRLF. Exploitation requires a reverse proxy that retains chunk extensions and treats the lone LF differently, enabling hidden requests and response corruption.

CVSS severity7.5
High
EPSS probability0.68%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

HTTP request smuggling in Netty 4.1.124.Final and earlier and 4.2.0.Alpha3 through 4.2.4.Final allows remote attackers to bypass access controls. HttpObjectDecoder treats a lone LF in an HTTP/1.1 chunk extension as the end of the chunk-size line instead of requiring CRLF. Exploitation requires a reverse proxy that retains chunk extensions and treats the lone LF differently, enabling hidden requests and response corruption.

The record

CVE
CVE-2025-58056
Published
Sep 3, 2025
Updated
Sep 5, 2025
Vendor
The Netty Project
Product
Netty
Classifications
CWE-444, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 3, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 5, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=<= 4.1.124.Final, < 4.1.125.Final
  2. Affected versionversion=>= 4.2.0.Alpha3, < 4.2.5.Final

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Netty Project · Nettyversion=<= 4.1.124.Final, < 4.1.125.Final; version=>= 4.2.0.Alpha3, < 4.2.5.Final

Published CVSS scores

2.9GitHub Security AdvisoriesCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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