CVE-2021-21409

mediumpriority · track · 26EPSS 0.049 · 92 %ileDEEURUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

4.93% (92nd) EPSS

CVSS 4.3 · medium

Is it mine?

44 products

Check your exposure

Who says so?

6 sources

cnnvd · enisa_euvd · fstec_bdu · cert_bund

EPSS · scored 2026-10-27

Netty is an open-source, asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers & clients. In Netty (io.netty:netty-codec-http2) before version 4.1.61.Final there is a vulnerability that enables request smuggling. The content-length header is not correctly validated if the request only uses a single Http2HeaderFrame with the endStream set to to true. This could lead to request smuggling if the request is proxied to a remote peer and translated to HTTP/1.1. This is a followup of GHSA-wm47-8v5p-wjpj/CVE-2021-21295 which did miss to fix this one case. This was fixed as part of 4.1.61.Final.

cvss

Technical severity, 0–10. One row per scoring source.

5.9

010

base score 0–10 · higher = more severe · hover a vector to decode

v2.04.3mediumAV:N/AC:M/Au:N/C:N/I:P/A:Nprimary · NVD / NIST USexploitability 8.6 · impact 2.9

v3.15.9mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:Nprimary · NVD / NIST USexploitability 2.2 · impact 3.6

v3.15.9mediumAV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:Nsecondary · FSTEC (BDU) RU

v3.15.9mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:Nsecondary · ENISA EU

v3.15.9mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:Nsecondary · security-advisories@github.comexploitability 2.2 · impact 3.6

v3.15.9mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:Nsecondary · OSV

v3.15.4mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N/E:Usecondary · CVSS-BT (t0sche)

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-444USprimaryCWE-444USCWE-444US

affected products (44)

Products and version ranges known to be affected.

Dell ECS <3.8.1.0all versionscert_bundDE
Dell PowerEdgeall versionscert_bundDEcpe:/h:dell:poweredge:-
IBM InfoSphere Information Serverall versionscert_bundDEcpe:/a:ibm:infosphere_information_server:-
Dell ECS< 3.8.1.0cert_bundDE
netty netty≤ < 4.1.61.Finalenisa_euvdEU
Apache Software Foundation Cassandra≤ 4.1.3fstec_bduRU
Apache Software Foundation netty≤ 4.1.61fstec_bduRU
АО «НППКТ» ОСОН ОСнова Оnyx≤ 2.1fstec_bduRU
ООО «РусБИТех-Астра» Astra Linux Special Edition≤ 1.7fstec_bduRU
Сообщество свободного программного обеспечения Debian GNU/Linux≤ 8fstec_bduRU
Сообщество свободного программного обеспечения Debian GNU/Linux≤ 10fstec_bduRU
Сообщество свободного программного обеспечения Debian GNU/Linux≤ 9fstec_bduRU
ФССП России ОС ТД АИС ФССП России≤ ИК6fstec_bduRU
debian debian linux= 10.0nvdUScpe:2.3:o:debian:debian_linux:*:*:*:*:*:*:*:*
netapp oncommand api servicesall versionsnvdUScpe:2.3:a:netapp:oncommand_api_services:*:*:*:*:*:*:*:*
netapp oncommand workflow automationall versionsnvdUScpe:2.3:a:netapp:oncommand_workflow_automation:*:*:*:*:*:*:*:*
netty netty< 4.1.61nvdUScpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*
oracle banking corporate lending process management= 14.2.0nvdUScpe:2.3:a:oracle:banking_corporate_lending_process_management:*:*:*:*:*:*:*:*
oracle banking corporate lending process management= 14.3.0nvdUScpe:2.3:a:oracle:banking_corporate_lending_process_management:*:*:*:*:*:*:*:*
oracle banking corporate lending process management= 14.5.0nvdUScpe:2.3:a:oracle:banking_corporate_lending_process_management:*:*:*:*:*:*:*:*

showing 20 of 44

advisories (4)

Vendor and ecosystem advisories describing this.

WID-SEC-W-2023-0809IBM QRadar SIEM: Mehrere SchwachstellenDeutsch2023-03-30csaf · cert_bundDE
Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in IBM QRadar SIEM ausnutzen, um beliebigen Programmcode auszuführen, Informationen offenzulegen, Informationen falsch darzustellen, einen Denial of Service Zustand herbeizuführen, Sicherheitsvorkehrungen zu umgehen, einen Cross-Site-Scripting-Angriff durchzuführen oder unbekannte Auswirkungen zu verursachen.
WID-SEC-W-2024-0794Dell ECS: Mehrere SchwachstellenDeutsch2024-04-04csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in Dell ECS ausnutzen, um seine Privilegien zu erweitern, beliebigen Programmcode mit Administratorrechten auszuführen, Informationen offenzulegen, Dateien zu manipulieren, einen Cross-Site-Scripting-Angriff durchzuführen, Sicherheitsvorkehrungen zu umgehen oder einen Denial of Service Zustand herbeizuführen.
WID-SEC-W-2025-1459Dell Data Protection Advisor: Mehrere SchwachstellenDeutsch2025-07-03csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in Dell Data Protection Advisor ausnutzen, um beliebigen Programmcode auszuführen, um einen Denial of Service Angriff durchzuführen, und um weitere nicht näher spezifizierte Angriffe durchzuführen.
GHSA-f256-j965-7f32Possible request smuggling in HTTP/2 due missing validation of content-length2021-03-30ghsa · osvUS
### Impact The content-length header is not correctly validated if the request only use a single Http2HeaderFrame with the endStream set to to true. This could lead to request smuggling if the request is proxied to a remote peer and translated to HTTP/1.1 This is a followup of https://github.com/netty/netty/security/advisories/GHSA-wm47-8v5p-wjpj which did miss to fix this one case. ### Patches This was fixed as part of 4.1.61.Final ### Workarounds Validation can be done by the user before proxy the request by validating the header.

also known as (4)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd fstec_bdu cert_bund nvd osv NVD CVE.org MITRE

published 2021-03-30modified 2026-06-17

related (553)

Related entries.

ID	severity	EPSS	exploitable	published
CVE-2026-48710US	medium6.5OT critical	70.3% (99th)	KEV	2026-05-26
Starlette is a lightweight ASGI framework/toolkit. Prior to version 1.0.1, the HTTP `Host` request header was not validated before being used to reconstruct `request.url`. Because…
CVE-2025-61884US	—OT critical	95.9% (100th)	KEV	2025-10-12
Vulnerability in the Oracle Configurator product of Oracle E-Business Suite (component: Runtime UI). Supported versions that are affected are 12.2.3-12.2.14. Easily exploitable vu…
CVE-2023-48365US	critical9.9OT critical	47.7% (99th)	KEV	2023-11-15
Qlik Sense Enterprise for Windows before August 2023 Patch 2 allows unauthenticated remote code execution, aka QB-21683. Due to improper validation of HTTP headers, a remote attack…
CVE-2023-41265US	critical9.9OT critical	88.2% (100th)	KEV	2023-08-29
An HTTP Request Tunneling vulnerability found in Qlik Sense Enterprise for Windows for versions May 2023 Patch 3 and earlier, February 2023 Patch 7 and earlier, November 2022 Patch…
CVE-2022-22536US	critical10.0OT critical	97.9% (100th)	KEV	2022-02-09
SAP NetWeaver Application Server ABAP, SAP NetWeaver Application Server Java, ABAP Platform, SAP Content Server 7.53 and SAP Web Dispatcher are vulnerable for request smuggling and…

+548 more

references (226)

External citations — patches, advisories, analysis.

scry

Attackers weaponise vulnerabilities like this against internet-exposed services. See what is exposed on your perimeter with a free passive scan.

Free scan