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Public proof of conceptFix available

CVE-2025-67735

A public proof of concept exists; no exploitation attested.

  • Published2025-12-16
  • Fixed in4.2.8.Final · 4.1.129.Final
  • WeaknessCWE-93

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

Netty is an asynchronous, event-driven network application framework. In versions prior to 4.1.129.Final and 4.2.8.Final, the `io.netty.handler.codec.http.HttpRequestEncoder` has a CRLF injection with the request URI when constructing a request. This leads to request smuggling when `HttpRequestEncoder` is used without proper sanitization of the URI. Any application / framework using `HttpRequestEncoder` can be subject to be abused to perform request smuggling using CRLF injection. Versions 4.1.129.Final and 4.2.8.Final fix the issue.

Timeline

dates in UTC
  1. 2025-12-1601:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-11-03 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2025-67735?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2025-67735?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

OSV · NVD
netty-codec-http
BranchAffectedFixed in
4.2≥ 4.2.0.Alpha1, < 4.2.8.Final4.2.8.Final
4.1< 4.1.129.Final4.1.129.Final
Netty
BranchAffectedFixed in
4.2≥ 4.2.0, < 4.2.84.2.8
4.1< 4.1.1294.1.129

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA1 product

As GitHub_M, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • netty
    Affected
    • = >= 4.2.0.Alpha1, < 4.2.8.Finalno fix stated
    • = < 4.1.129.Finalno fix stated

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2025-12-16

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • airbyte-serverMinimOSall versions · fixed in 2.2.0-r0
  • apache-hiveCleanStartall versions · fixed in 3.1.3-r3
  • apache-hiveCleanStartall versions · fixed in 4.0.0-r0
  • apache-hiveCleanStartall versions · fixed in 4.2.0-r1
  • apicurio-registryCleanStartall versions · fixed in 3.1.7-r6
  • cloud-config-serverCleanStartall versions · fixed in 4.3.2-r3
  • cloudwatch-exporterMinimOSall versions · fixed in 0.17.0-r0
  • conductor-fipsMinimOSall versions · fixed in 3.32.1-r0

124 more package ranges on OSV.dev

Vendor advisories

  • CVE-2025-67735 Red Hat Product Security2 products fixed · 76 known affected

    netty-codec-http: Netty (netty-codec-http): Request Smuggling via CRLF Injection

    netty-codec-http as a component of Cryostat 4 · netty-codec-http2 as a component of Cryostat 4 · netty-codec-http as a component of Logging Subsystem for Red Hat OpenShift · +73 more

  • RHSA-2026:1965 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: Red Hat build of Quarkus 3.27.2 release and security update

  • RHSA-2026:1899 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: Red Hat build of Quarkus 3.20.5 release and security update

Full record on NVD

Fix

  1. Update netty-codec-http to 4.2.8.Final · 4.1.129.Final
  2. Vendor fix Red Hat Product Security RHSA-2026:1965 · 1 productBefore applying this update, make sure all previously released errata relevant to your system have been applied. For details on how to apply this update, refer to: https://access.redhat.com/articles/11258
  3. Workaround from the vendor Red Hat Product Security RHSA-2026:1965 · 1,028 productsMitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
  4. No fix available, says the vendor Red Hat Product Security CVE-2025-67735 · 75 productsFix deferred
  5. No fix available, says the vendor Red Hat Product Security CVE-2025-67735 · 1 productAffected

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub
Metasploit modules
none listed
Metasploit Framework

Sources

  • NVDCVE recordread 2026-10-23
  • CISA-ADPSSVC decisionpoc2025-12-16
  • OpenCVESSVC decisionpoc—
  • CNACVSS 3.16.5known since 2026-10-23
  • CNAweakness (CWE)CWE-93known since 2026-10-23
  • FIRST EPSSEPSS score0.3 %2026-11-03
  • OSVaffected packages—
  • GitHub AdvisoriesadvisoryMODERATE2025-12-15

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Published
2025-12-16
Last Modified
2026-10-14
NVD status
Analyzed
GitHub Advisory
GHSA-84h7-rjj3-6jx4

Frequently asked questions

What is CVE-2025-67735?

Netty is an asynchronous, event-driven network application framework. In versions prior to 4.1.129.Final and 4.2.8.Final, the `io.netty.handler.codec.http.HttpRequestEncoder` has a CRLF injection with the request URI when constructing a request. This leads to request smuggling when `HttpRequestEncoder` is used without proper sanitization of the URI. Any application / framework using `HttpRequestEncoder` can be subject to be abused to perform request smuggling using CRLF injection. Versions 4.1.129.Final and 4.2.8.Final fix the issue.

Is CVE-2025-67735 actively exploited?

A proof-of-concept exploit exists for CVE-2025-67735, but active exploitation has not been confirmed at this time.

What is the CVSS score for CVE-2025-67735?

CVE-2025-67735 has a CVSS v3 base score of 6.5 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N.

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