Red Hat: OWASP Top Ten 2017 Category A9 - Using Components with Known Vulnerabilities (CVE-2026-93566)
Published Last modified Sources: SUSE, Red Hat, BSI, CVE.org
What is affected, what to do
A flaw was found in Netty. A remote attacker could exploit this by sending a specially crafted HTTP request that includes control characters within the chunk-size line.
Update open source Netty to version 4.1.138.Final, open source Netty to version 4.2.18.Final.
- Affected
- open source Netty
< *..4.1.138.Final - open source Netty
< *..4.2.18.Final
- open source Netty
- Fixed in
- open source Netty
4.1.138.Final - open source Netty
4.2.18.Final
- open source Netty
Not sure whether and how you are affected? Ask a question about this vulnerability
Metrics
6.5
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: NVD, CVSS v3
6.5
CVSS v3
Severity Medium on the scale from 0 to 10.
Source: SUSE, Red Hat, BSI, CVE.org
0.5 %
EPSS score
Low — model estimates < 1% exploitation likelihood.
Source: FIRST EPSS, percentile 41.2
Show all metrics
- Severity
- Medium
Priority (0–325)
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 74.01 Methodology
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- no public PoC known
XIEM Effective CVSS
XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.
Read in glossary- 6.5 Methodology
CVSS v3
CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.
Read in glossary- 6.5
EPSS score
The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.
Read in glossary- 0.5 %
- Low — model estimates < 1% exploitation likelihood.
EPSS percentile
The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.
Read in glossary- 41.2
- High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- —
- Published
CWE
CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.
Read in glossary- CWE-1035
Detection rules
No NEOSEC detection rule is available for this vulnerability yet.
Classification under NIS2 and CRA
Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.
NIS2
NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.
Read in glossary- Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.
CRA
The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.
Read in glossary- From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001
ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.
Read in glossary- Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.
Description
A flaw was found in Netty. A remote attacker could exploit this by sending a specially crafted HTTP request that includes control characters within the chunk-size line. This bypasses the intended strict validation, allowing the attacker to inject arbitrary HTTP requests. This vulnerability can lead to HTTP request smuggling, potentially resulting in information disclosure or other unauthorized actions.
Source: suse_csaf, redhat_csaf, BSI WID Portal, BSI CSAF, NVD (NIST), cvelistv5
Affected products
The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.
| Affected versions | Fixed in | ||
|---|---|---|---|
| Red Hat | Red Hat AMQ Broker 7 |
|
|
| Red Hat | Red Hat AMQ Clients |
|
|
| Red Hat | Red Hat build of Apache Camel 4 for Quarkus 3 |
|
|
| Red Hat | Red Hat build of Apache Camel for Spring Boot 4 |
|
|
| Red Hat | Red Hat build of Apicurio Registry 3 |
|
|
| Red Hat | Red Hat Build of Debezium 3.6 |
|
|
| Red Hat | Red Hat Build of Keycloak |
|
|
| Red Hat | Red Hat build of Quarkus 3.27.5.SP2 |
|
|
| Red Hat | Red Hat build of Quarkus 3.33.3.SP2 |
|
|
| Red Hat | Red Hat Data Grid 8 |
|
|
| Red Hat | Red Hat Fuse 7 |
|
|
| Red Hat | Red Hat JBoss Enterprise Application Platform 7 |
|
|
| Red Hat | Red Hat JBoss Enterprise Application Platform 8 |
|
|
| Red Hat | Red Hat Single Sign-On 7 |
|
|
| Open Source | Netty |
|
|
Vendors and products
- Open Source Netty
- Red Hat Red Hat Amq Broker 7
- Red Hat Red Hat Amq Clients
- Red Hat Red Hat Build Of Apache Camel 4 For Quarkus 3
- Red Hat Red Hat Build Of Apache Camel For Spring Boot 4
- Red Hat Red Hat Build Of Apicurio Registry 3
- Red Hat Red Hat Build Of Debezium 3.6
- Red Hat Red Hat Build Of Keycloak
- Red Hat Red Hat Build Of Quarkus 3.27.5.sp2
- Red Hat Red Hat Build Of Quarkus 3.33.3.sp2
- Red Hat Red Hat Data Grid 8
- Red Hat Red Hat Fuse 7
Weakness classes (CWE)
CWE-1035OWASP Top Ten 2017 Category A9 - Using Components with Known Vulnerabilities
Category
Entry at MITRE CWE-1035
References & sources
- access.redhat.comsecurity/cve/CVE-2026-93566Vulnerability database, x_refsource_REDHAT
- bugzilla.redhat.comRHBZ#2536954Issue tracking, x_refsource_REDHAT
- access.redhat.comRHSA-2026:69470Vendor advisory, x_refsource_REDHAT
- access.redhat.comRHSA-2026:69440Vendor advisory, x_refsource_REDHAT
- access.redhat.comRHSA-2026:83612Vendor advisory, x_refsource_REDHAT
Changes to this CVE
Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).
Record modifiedRed Hat
New references:Show 2 original changes
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/93xxx/CVE-2026-93566.json">CVE-2026-93566</a>Reference added —https://access.redhat.com/errata/RHSA-2026:83612Source identifier: secalert@redhat.com
Record modifiedRed Hat
1 individual change: Affected versions (publisher)
Show the original change
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/93xxx/CVE-2026-93566.json">CVE-2026-93566</a>Source identifier: secalert@redhat.com
Record modifiedRed Hat
1 individual change: Affected versions (publisher)
Show the original change
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/93xxx/CVE-2026-93566.json">CVE-2026-93566</a>Source identifier: secalert@redhat.com
Record modifiedRed Hat
New references:Show the original change
Individual changes of this event as published by NVD Type Action Before After Reference added —https://access.redhat.com/errata/RHSA-2026:69440Source identifier: secalert@redhat.com
Record modifiedCISA ADP
CISA assessment (SSVC): exploitation: none known, automatable: yes
Show the original change
Individual changes of this event as published by NVD Type Action Before After SSVC assessment added —{"id":"CVE-2026-93566","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"partial"}],"version":"2.0.3","timestamp":"2026-09-22T14:28:28.241291Z"}Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0
Show 4 older changes
Record modifiedRed Hat
New references:Show 2 original changes
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/93xxx/CVE-2026-93566.json">CVE-2026-93566</a>Reference added —https://access.redhat.com/errata/RHSA-2026:69470Source identifier: secalert@redhat.com
Record modifiedRed Hat
1 individual change: Affected versions (publisher)
Show the original change
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/93xxx/CVE-2026-93566.json">CVE-2026-93566</a>Source identifier: secalert@redhat.com
Record modifiedRed Hat
Description added or changed
Show 2 original changes
Individual changes of this event as published by NVD Type Action Before After Description changed ### Summary Netty skips strict chunk size line validation when the line has no chunk extension (`;`), so a chunk size line containing an embedded bare CR (e.g. `0\rX`) is accepted instead of rejected, enabling HTTP request smuggling. ### Details `io.netty.handler.codec.http.HttpObjectDecoder#checkChunkExtensions` only runs the strict validator `HttpChunkLineValidatingByteProcessor` when a `;` is present: ```java int extensionsStart = line.bytesBefore((byte) ';'); if (extensionsStart == -1) { return; } ``` According to RFC 9112 https://datatracker.ietf.org/doc/html/rfc9112#appendix-A `chunk-size = 1*HEXDIG` ### PoC ```java @Test public void test() { String requestStr = "POST / HTTP/1.1\r\n" + "Host: localhost\r\n" + "Transfer-Encoding: chunked\r\n\r\n" + "0\rX\r\n" + "\r\n" + "GET /smuggled HTTP/1.1\r\n" + "Host: localhost\r\n" + "Content-Length: 0\r\n" + "\r\n"; EmbeddedChannel channel = new EmbeddedChannel(new HttpRequestDecoder()); assertTrue(channel.writeInbound(Unpooled.copiedBuffer(requestStr, ChA flaw was found in Netty. A remote attacker could exploit this by sending a specially crafted HTTP request that includes control characters within the chunk-size line. This bypasses the intended strict validation, allowing the attacker to inject arbitrary HTTP requests. This vulnerability can lead to HTTP request smuggling, potentially resulting in information disclosure or other unauthorized actions.Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/93xxx/CVE-2026-93566.json">CVE-2026-93566</a>Source identifier: secalert@redhat.com
ReceivedRed Hat
CVSS V3.1: AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Weakness type: CWE-1035
Description added or changed
Show 6 original changes
Individual changes of this event as published by NVD Type Action Before After Description added —### Summary Netty skips strict chunk size line validation when the line has no chunk extension (`;`), so a chunk size line containing an embedded bare CR (e.g. `0\rX`) is accepted instead of rejected, enabling HTTP request smuggling. ### Details `io.netty.handler.codec.http.HttpObjectDecoder#checkChunkExtensions` only runs the strict validator `HttpChunkLineValidatingByteProcessor` when a `;` is present: ```java int extensionsStart = line.bytesBefore((byte) ';'); if (extensionsStart == -1) { return; } ``` According to RFC 9112 https://datatracker.ietf.org/doc/html/rfc9112#appendix-A `chunk-size = 1*HEXDIG` ### PoC ```java @Test public void test() { String requestStr = "POST / HTTP/1.1\r\n" + "Host: localhost\r\n" + "Transfer-Encoding: chunked\r\n\r\n" + "0\rX\r\n" + "\r\n" + "GET /smuggled HTTP/1.1\r\n" + "Host: localhost\r\n" + "Content-Length: 0\r\n" + "\r\n"; EmbeddedChannel channel = new EmbeddedChannel(new HttpRequestDecoder()); assertTrue(channel.writeInbound(Unpooled.copiedBuffer(requestStr, ChCVSS added —AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:NWeakness type (CWE) added —CWE-1035Affected versions (publisher) added —New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/93xxx/CVE-2026-93566.json">CVE-2026-93566</a>Reference added —https://access.redhat.com/security/cve/CVE-2026-93566Reference added —https://bugzilla.redhat.com/show_bug.cgi?id=2536954Source identifier: secalert@redhat.com
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