BlackTreeCVE Intelligence
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Full vulnerability report · 2026
CVE-2026-42580High confidence

Netty: HTTP Request Smuggling due to incorrect chunk size parsing

netty · netty

Official source article: GitHub GHSA-M4CV-J2PX-7723 ↗. Check the applicable product and release in the original source.

6.5MediumCVSS 3.1
Recommended action
Within 7 days

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Fix not verified
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:High, raised one band.upgradedsince 14 May 2026

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • A structured source references public exploit or proof-of-concept material.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 0.36% for the current model date.

Compensating controls

  • Restrict the affected network interface to trusted sources where business-safe.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs netty netty and falls inside the recorded affected range.
  2. Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 30 daysRemediation target: Within 180 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Distribution package intelligence

Release-specific package status

Debian, ubuntu findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.

5 package states
Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Distribution releaseSource packageVendor stateFixed versionEvidence
Debian trixietrixie · sourcenettyAffected, no fix publishedDebian currently tracks this release as open.Not published in this feedDebian Security Tracker ↗Source updated 8 Oct 2026
Debian bookwormbookworm · sourcenettyAffected, no fix publishedDebian currently tracks this release as open.Not published in this feedDebian Security Tracker ↗Source updated 8 Oct 2026
Debian forkyforky · sourcenettyAffected, no fix publishedDebian currently tracks this release as open.Not published in this feedDebian Security Tracker ↗Source updated 8 Oct 2026
Debian sidsid · sourcenettyAffected, no fix publishedDebian currently tracks this release as open.Not published in this feedDebian Security Tracker ↗Source updated 8 Oct 2026
Ubuntu 24.04 LTSnoble · esm-appsnettyUnder evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.Not published in this feedCanonical Ubuntu Security ↗Source updated 7 Oct 2026
Open-source package ranges4 source-attributed ranges

These OSV and GitHub advisory ranges apply only to the named package and ecosystem. A listed fixed version is not a universal product patch or proof that an update is installed.

Ecosystem and packageAffected rangeFirst fixed versionEvidence
Mavenio.netty:netty-codec-httpECOSYSTEM: introduced 4.2.0.Alpha1; fixed 4.2.13.Final4.2.13.FinalOSV record ↗aggregator derived · 10 Sep 2026
Mavenio.netty:netty-codec-httpECOSYSTEM: introduced 0; fixed 4.1.133.Final4.1.133.FinalOSV record ↗aggregator derived · 10 Sep 2026
mavenio.netty:netty-codec-http>= 4.2.0.Alpha1, <= 4.2.12.Final4.2.13.FinalGitHub advisory ↗upstream repository advisory · 14 May 2026
mavenio.netty:netty-codec-http<= 4.1.132.Final4.1.133.FinalGitHub advisory ↗upstream repository advisory · 14 May 2026
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2026-30123

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Fix not verified
01

What, why and how

Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, Netty's chunk size parser silently overflows int, enabling request smuggling attacks. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.

What

Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, Netty's chunk size parser silently overflows int, enabling request smuggling attacks. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.

Why

The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, Netty's chunk size parser silently overflows int, enabling request smuggling attacks. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.

Why

The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Reference recorded

A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.

Likely attack path
a network path → Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-444 ↗

CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling'). The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CNoneConfidentiality impact: No direct loss is represented by this metric.ILowIntegrity impact: A successful attack can cause a limited loss.ALowAvailability impact: A successful attack can cause a limited loss.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedCWE-444Public exploit reference
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

BSI · German · WID-SEC-2026-1372Netty: Mehrere Schwachstellen

Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Netty ausnutzen, um Sicherheitsmaßnahmen zu umgehen, Daten zu manipulieren, vertrauliche Informationen offenzulegen oder einen Denial-of-Service-Zustand zu verursachen.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20260520Security Bulletin 20 May 2026

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 20 May 2026, published on 20 May 2026. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-1206Multiples vulnérabilités dans les produits IBM

d?id=CVE-2026-42198 Référence CVE CVE-2026-42264 https://www.cve.org/CVERecord?id=CVE-2026-42264 Référence CVE CVE-2026-42402 https://www.cve.org/CVERecord?id=CVE-2026-42402 Référence CVE CVE-2026-42403 https://www.cve.org/CVERecord?id=CVE-2026-42403 Référence CVE CVE-2026-42404 https://www.cve.org/CVERecord?id=CVE-2026-42404 Référence CVE CVE-2026-42440 https://www.cve.org/CVERecord?id=CVE-2026-42440 Référence CVE CVE-2026-42577 https://www.cve.org/CVERecord?id=CVE-2026-42577 Référence CVE CVE-2026-42578 https://www.cve.org/CVERecord?id=CVE-2026-42578 Référence CVE CVE-2026-42579 https://www.cve.org/CVERecord?id=CVE-2026-42579 Référence CVE CVE-2026-42580 https://www.cve.org/CVERecord?id=CVE-2026-42580 Référence CVE CVE-2026-42581 https://www.cve.org/CVERecord?id=CVE-2026-42581 Référence CVE CVE-2026-42583 https://www.cve.org/CVERecord?id=CVE-2026-42583 Référence CVE CVE-2026-42584 https://www.cve.org/CVERecord?id=CVE-2026-42584 Référence CVE CVE-2026-42585 https://www.cve.org/CVERecord?id=CVE-2026-42585 Référence CVE CVE-2026-42586 https://www.cve.org/CVERecord?id=CVE-2026-42586 Référence CVE CVE-2026-42587 https://www.cve.org/CVERecord?id=CVE-2026-42587 Référence CVE CVE-2026-43827 https://www.cve.org/CVERecord?id=CVE-2026-43827 Référence CVE CVE-2026-43828 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-1165Multiples vulnérabilités dans les produits IBM

d?id=CVE-2026-42043 Référence CVE CVE-2026-42044 https://www.cve.org/CVERecord?id=CVE-2026-42044 Référence CVE CVE-2026-42264 https://www.cve.org/CVERecord?id=CVE-2026-42264 Référence CVE CVE-2026-42402 https://www.cve.org/CVERecord?id=CVE-2026-42402 Référence CVE CVE-2026-42403 https://www.cve.org/CVERecord?id=CVE-2026-42403 Référence CVE CVE-2026-42404 https://www.cve.org/CVERecord?id=CVE-2026-42404 Référence CVE CVE-2026-42498 https://www.cve.org/CVERecord?id=CVE-2026-42498 Référence CVE CVE-2026-42577 https://www.cve.org/CVERecord?id=CVE-2026-42577 Référence CVE CVE-2026-42578 https://www.cve.org/CVERecord?id=CVE-2026-42578 Référence CVE CVE-2026-42580 https://www.cve.org/CVERecord?id=CVE-2026-42580 Référence CVE CVE-2026-42581 https://www.cve.org/CVERecord?id=CVE-2026-42581 Référence CVE CVE-2026-42584 https://www.cve.org/CVERecord?id=CVE-2026-42584 Référence CVE CVE-2026-42585 https://www.cve.org/CVERecord?id=CVE-2026-42585 Référence CVE CVE-2026-42586 https://www.cve.org/CVERecord?id=CVE-2026-42586 Référence CVE CVE-2026-42587 https://www.cve.org/CVERecord?id=CVE-2026-42587 Référence CVE CVE-2026-42778 https://www.cve.org/CVERecord?id=CVE-2026-42778 Référence CVE CVE-2026-42779 https://www.cve.org/CVERecord?id=CVE-2026-42779 Référence CVE CVE-2026-43512 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-1032Multiples vulnérabilités dans les produits IBM

d?id=CVE-2026-34477 Référence CVE CVE-2026-34478 https://www.cve.org/CVERecord?id=CVE-2026-34478 Référence CVE CVE-2026-34479 https://www.cve.org/CVERecord?id=CVE-2026-34479 Référence CVE CVE-2026-34480 https://www.cve.org/CVERecord?id=CVE-2026-34480 Référence CVE CVE-2026-35091 https://www.cve.org/CVERecord?id=CVE-2026-35091 Référence CVE CVE-2026-35092 https://www.cve.org/CVERecord?id=CVE-2026-35092 Référence CVE CVE-2026-41254 https://www.cve.org/CVERecord?id=CVE-2026-41254 Référence CVE CVE-2026-41417 https://www.cve.org/CVERecord?id=CVE-2026-41417 Référence CVE CVE-2026-42578 https://www.cve.org/CVERecord?id=CVE-2026-42578 Référence CVE CVE-2026-42580 https://www.cve.org/CVERecord?id=CVE-2026-42580 Référence CVE CVE-2026-42581 https://www.cve.org/CVERecord?id=CVE-2026-42581 Référence CVE CVE-2026-42583 https://www.cve.org/CVERecord?id=CVE-2026-42583 Référence CVE CVE-2026-42584 https://www.cve.org/CVERecord?id=CVE-2026-42584 Référence CVE CVE-2026-42585 https://www.cve.org/CVERecord?id=CVE-2026-42585 Référence CVE CVE-2026-42587 https://www.cve.org/CVERecord?id=CVE-2026-42587 Référence CVE CVE-2026-4410 https://www.cve.org/CVERecord?id=CVE-2026-4410 Référence CVE CVE-2026-44405 https://www.cve.org/CVERecord?id=CVE-2026-44405 Référence CVE CVE-2026-44431 https://www.cve.org/CVERecord?id=CV

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-0986Multiples vulnérabilités dans les produits IBM

ord?id=CVE-2026-40164 Référence CVE CVE-2026-4046 https://www.cve.org/CVERecord?id=CVE-2026-4046 Référence CVE CVE-2026-41254 https://www.cve.org/CVERecord?id=CVE-2026-41254 Référence CVE CVE-2026-41284 https://www.cve.org/CVERecord?id=CVE-2026-41284 Référence CVE CVE-2026-41293 https://www.cve.org/CVERecord?id=CVE-2026-41293 Référence CVE CVE-2026-41417 https://www.cve.org/CVERecord?id=CVE-2026-41417 Référence CVE CVE-2026-42496 https://www.cve.org/CVERecord?id=CVE-2026-42496 Référence CVE CVE-2026-42497 https://www.cve.org/CVERecord?id=CVE-2026-42497 Référence CVE CVE-2026-42498 https://www.cve.org/CVERecord?id=CVE-2026-42498 Référence CVE CVE-2026-42580 https://www.cve.org/CVERecord?id=CVE-2026-42580 Référence CVE CVE-2026-42581 https://www.cve.org/CVERecord?id=CVE-2026-42581 Référence CVE CVE-2026-42583 https://www.cve.org/CVERecord?id=CVE-2026-42583 Référence CVE CVE-2026-42584 https://www.cve.org/CVERecord?id=CVE-2026-42584 Référence CVE CVE-2026-42585 https://www.cve.org/CVERecord?id=CVE-2026-42585 Référence CVE CVE-2026-42587 https://www.cve.org/CVERecord?id=CVE-2026-42587 Référence CVE CVE-2026-42944 https://www.cve.org/CVERecord?id=CVE-2026-42944 Référence CVE CVE-2026-42959 https://www.cve.org/CVERecord?id=CVE-2026-42959 Référence CVE CVE-2026-43020 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-0810Multiples vulnérabilités dans les produits IBM

d?id=CVE-2026-42042 Référence CVE CVE-2026-42043 https://www.cve.org/CVERecord?id=CVE-2026-42043 Référence CVE CVE-2026-42044 https://www.cve.org/CVERecord?id=CVE-2026-42044 Référence CVE CVE-2026-42264 https://www.cve.org/CVERecord?id=CVE-2026-42264 Référence CVE CVE-2026-42402 https://www.cve.org/CVERecord?id=CVE-2026-42402 Référence CVE CVE-2026-42403 https://www.cve.org/CVERecord?id=CVE-2026-42403 Référence CVE CVE-2026-42404 https://www.cve.org/CVERecord?id=CVE-2026-42404 Référence CVE CVE-2026-42502 https://www.cve.org/CVERecord?id=CVE-2026-42502 Référence CVE CVE-2026-42506 https://www.cve.org/CVERecord?id=CVE-2026-42506 Référence CVE CVE-2026-42580 https://www.cve.org/CVERecord?id=CVE-2026-42580 Référence CVE CVE-2026-42581 https://www.cve.org/CVERecord?id=CVE-2026-42581 Référence CVE CVE-2026-42583 https://www.cve.org/CVERecord?id=CVE-2026-42583 Référence CVE CVE-2026-42584 https://www.cve.org/CVERecord?id=CVE-2026-42584 Référence CVE CVE-2026-42585 https://www.cve.org/CVERecord?id=CVE-2026-42585 Référence CVE CVE-2026-42587 https://www.cve.org/CVERecord?id=CVE-2026-42587 Référence CVE CVE-2026-5588 https://www.cve.org/CVERecord?id=CVE-2026-5588 Référence CVE CVE-2026-5598 https://www.cve.org/CVERecord?id=CVE-2026-5598 Référence CVE CVE-2026-5795 https://www.cve.org/CVERecord?id=CVE-2

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2026-016411Nettyにおける複数の脆弱性

Nettyは非同期でイベント駆動型のネットワークアプリケーションフレームワークです。4.2.13.Finalおよび4.1.133.Final以前のバージョンでは、Nettyのチャンクサイズパーサがint型を静かにオーバーフローさせ、リクエストスマグリング攻撃を可能にしていました。この脆弱性は4.2.13.Finalおよび4.1.133.Finalで修正されました。

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Fix not verified
Affected
  • netty: >= 4.2.0.Alpha1, < 4.2.13.Final, < 4.1.133.Final
  • netty-codec-http: >= 4.2.0.Alpha1, < 4.2.13.Final, < 4.1.133.Final
Fixed
No fixed version is explicitly recorded in the structured CVE data.
Action
No verified patch reference is present in the current structured sources. Check the vendor advisory before making a change.
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 13 May 2026 · Last source change 14 May 2026, 18:21 UTC · CWE-444 · Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2026-30123
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD enriched

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗

No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.

Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2026-42580 · cve.blacktree.nl