CVE-2026-42581: Netty: HTTP/1.0 TE+CL Coexistence Bypasses Smuggling Sanitization
Noroxi assessment
Priority: Monitor (action score 39/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 0.63% (FIRST EPSS); higher than 50.7% of all records.
- Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
- According to CISA the attack is automatable: targets can be found by mass scanning.
- Fixed version: netty netty 4.2.13.Final.
- Severity is disputed: the assigning authority (CNA) scores it 5.8, NVD 9.8.
Low priority for now. Upgrade to netty netty 4.2.13.Final or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
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.
- Published
- May 13, 2026
- Updated
- Nov 11, 2026
- EPSS
- 0.6% · 50th percentile
- CWE
- CWE-444
Report tools
Action score
39
Low priority for now.
- CVSS
- 39 / 40 · 9.8 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.6%
CISA SSVC decision
- Exploitation
- proof of concept
- Automatable
- yes
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- 9.8
- CNA · GitHub_M
- 5.8
- 4.0 point gap
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
Is your version affected? Check itNoroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| netty | netty | cpe:2.3:a:netty:netty |
Versions reported by the vendor
Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.
netty netty
- >= 4.2.0.Alpha1, < 4.2.13.Final, < 4.1.133.Finalaffected
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- netty nettybefore 4.1.133
- netty netty4.2.0 and later · before 4.2.13
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | netty | from 0 | — |
| Maven | io.netty:netty-codec-http | from 4.2.0.Alpha1 · before 4.2.13.Final | 4.2.13.Final |
| Maven | io.netty:netty-codec-http | before 4.1.133.Final | 4.1.133.Final |
| openSUSE:Tumbleweed | netty | before 4.1.133-1.1 | 4.1.133-1.1 |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-cli | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-commons | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-core-client | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-dto | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-hornetq-protocol | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-hqclient-protocol | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-jdbc-store | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-jms-client | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-jms-server | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-journal | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-ra | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-selector | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-server | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-service-extensions | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-activemq-artemis-tools | before 0:2.16.0-22.redhat_00057.1.el7eap | 0:2.16.0-22.redhat_00057.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-glassfish-jsf | before 0:2.3.14-11.SP11_redhat_00001.1.el7eap | 0:2.3.14-11.SP11_redhat_00001.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-ironjacamar | before 0:1.5.26-2.Final_redhat_00001.1.el7eap | 0:1.5.26-2.Final_redhat_00001.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-ironjacamar-common-api | before 0:1.5.26-2.Final_redhat_00001.1.el7eap | 0:1.5.26-2.Final_redhat_00001.1.el7eap |
| Red Hat:jboss_enterprise_application_platform_els:7.4::el7 | eap7-ironjacamar-common-impl | before 0:1.5.26-2.Final_redhat_00001.1.el7eap | 0:1.5.26-2.Final_redhat_00001.1.el7eap |
+96
Same product
netty: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-47691Netty has Insufficient Bailiwick Validation for NS Records40Plan
- CVE-2026-45674Netty Vulnerable to DNS Cache Poisoning via Missing Bailiwick Checks in CNAME Records40Plan
- CVE-2019-20445HttpObjectDecoder.java in Netty before 4.1.44 allows a Content-Length header to be accompanied by a second Content-Length header, or by a…40Plan
Published before and after this one in the same product
- ← EarlierCVE-2026-42579May 13, 2026 · Netty: DNS Codec Input Validation Bypass in Netty (Encoder + Decoder)36Monitor
- ← EarlierCVE-2026-42580May 13, 2026 · Netty: HTTP Request Smuggling due to incorrect chunk size parsing26Monitor
- Later →CVE-2026-42582May 13, 2026 · Netty: HTTP/3 QPACK literal unbounded allocation30Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| netty netty | 4.2.13.Final · description | Vendor (CNA) |
| Maven:io.netty:netty-codec-http | 4.1.133.Final | Package registry (OSV) |
| Maven:io.netty:netty-codec-http | 4.2.13.Final | Package registry (OSV) |
| opensuse:netty | 4.1.133-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| red hat:eap8-eap-product-conf-parent | 0:801.7.1-1.GA_redhat_00001.1.el10eap · Red Hat:jboss_enterprise_application_platform:8.1::el10 | Package registry (OSV) |
| red hat:eap8-eap-product-conf-wildfly-ee-feature-pack | 0:801.7.1-1.GA_redhat_00001.1.el10eap · Red Hat:jboss_enterprise_application_platform:8.1::el10 | Package registry (OSV) |
| red hat:eap8-netty | 0:4.1.135-1.Final_redhat_00001.1.el10eap · Red Hat:jboss_enterprise_application_platform:8.1::el10 | Package registry (OSV) |
| red hat:eap8-netty-buffer | 0:4.1.135-1.Final_redhat_00001.1.el10eap · Red Hat:jboss_enterprise_application_platform:8.1::el10 | Package registry (OSV) |
| red hat:eap8-netty-codec | 0:4.1.135-1.Final_redhat_00001.1.el10eap · Red Hat:jboss_enterprise_application_platform:8.1::el10 | Package registry (OSV) |
| red hat:eap8-netty-codec-dns | 0:4.1.135-1.Final_redhat_00001.1.el10eap · Red Hat:jboss_enterprise_application_platform:8.1::el10 | Package registry (OSV) |
| red hat:eap8-netty-codec-http | 0:4.1.135-1.Final_redhat_00001.1.el10eap · Red Hat:jboss_enterprise_application_platform:8.1::el10 | Package registry (OSV) |
| red hat:eap8-netty-codec-socks | 0:4.1.135-1.Final_redhat_00001.1.el10eap · Red Hat:jboss_enterprise_application_platform:8.1::el10 | Package registry (OSV) |
| red hat:eap8-netty-common | 0:4.1.135-1.Final_redhat_00001.1.el10eap · Red Hat:jboss_enterprise_application_platform:8.1::el10 | Package registry (OSV) |
| red hat:eap8-netty-handler | 0:4.1.135-1.Final_redhat_00001.1.el10eap · Red Hat:jboss_enterprise_application_platform:8.1::el10 | Package registry (OSV) |
| red hat:eap8-netty-handler-proxy | 0:4.1.135-1.Final_redhat_00001.1.el10eap · Red Hat:jboss_enterprise_application_platform:8.1::el10 | Package registry (OSV) |
| red hat:eap8-netty-resolver | 0:4.1.135-1.Final_redhat_00001.1.el10eap · Red Hat:jboss_enterprise_application_platform:8.1::el10 | Package registry (OSV) |
| suse:netty | 4.1.133-150200.4.46.1 · SUSE:Linux Enterprise Module for Package Hub 15 SP7 | Package registry (OSV) |
| suse:netty-tcnative | 2.0.77-150200.3.39.1 · SUSE:Linux Enterprise Module for Development Tools 15 SP7 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
- CVE-2026-425840 days apartNetty: HttpClientCodec response desynchronization36Monitor
- CVE-2026-425850 days apartNetty: HTTP Request Smuggling due to malformed Transfer-Encoding30Monitor
- CVE-2026-3387047 days apartNetty: HTTP Request Smuggling via Chunked Extension Quoted-String Parsing30Monitor
- CVE-2026-5990077 days apartNetty codec-http2: Lack of Host Header Deduplication in HTTP/2→HTTP/1.x Translation Leads to Request Routing Bypass27Monitor
- CVE-2026-89044120 days apartNetty 4.1.133.Final through 4.1.137.Final and 4.2.13.Final through 4.2.17.Final HTTP Request Smuggling via Transfer-Encoding27Monitor
- CVE-2026-100659136 days apartNetty 4.2.0 through 4.2.17 HTTP/3 Request Routing Bypass27Monitor
Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · public bounty program.
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-444 · Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
ATT&CK techniques
—
Change log (1)
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (18 more)Show less
- 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/errata/RHSA-2026:49700
- access.redhat.com/errata/RHSA-2026:49701
- access.redhat.com/errata/RHSA-2026:53644
- access.redhat.com/errata/RHSA-2026:53645
- access.redhat.com/errata/RHSA-2026:53646
- access.redhat.com/errata/RHSA-2026:54435
- access.redhat.com/errata/RHSA-2026:65126
- access.redhat.com/errata/RHSA-2026:66488
- access.redhat.com/errata/RHSA-2026:66545
- access.redhat.com/security/cve/CVE-2026-42581
- bugzilla.redhat.com/show_bug.cgi?id=2477232
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42581.json
Vendor advisories and official records. Exploit/PoC links are deliberately left out.