VDB

CVE-2021-21409

CVE-2021-21409 PUBLISHED CVSS 5.9 MEDIUM

Possible request smuggling in HTTP/2 due missing validation of content-length

Reported by github_m · Published March 30, 2021

netty is fixed in 4.1.61 (Maven Central)

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.

Fixed versions

Upgrade to a fixed version or later. Language registries are listed first, then Linux distributions, then vendor products.

PackageEcosystemFixed in
io.netty:nettyMaven Central4.1.61
io.netty:netty-codecMaven Central4.1.61
io.helidon:helidon-dependenciesMaven Central[2.4.0
io.netty:netty-codec-http2Maven Central4.1.61.Final, 4.1.61
io.netty:netty-codec-httpMaven Central4.1.61
quarkusquarkus1.13.7
nosql_databaseoracle21.1.12
jd_edwards_enterpriseone_toolsoracle9.2.6.3
nettyUbuntu:Pro:16.04:LTS1:4.0.34-1ubuntu0.1~esm1
nettynetty4.1.61
nettyUbuntu:Pro:18.04:LTS1:4.1.7-4ubuntu0.1+esm2
nettyUbuntu:Pro:20.04:LTS1:4.1.45-1ubuntu0.1~esm1

1 more packages have a fixed version. See every fix in Lookup.

Risk scores

CVSS 3.1
5.9
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

Affected products

VendorProductVersions
nettynetty< 4.1.61.Final
nettynetty0

Timeline

  • Mar 30, 2021 CVE Published
  • Apr 14, 2021 EPSS Score (30 in total, the first dated here)
  • Mar 7, 2026 Distribution Patch (25 in total, the first dated here)
  • Mar 7, 2026 Security Advisory (30 in total, the first dated here)
  • Aug 26, 2026 Coalition ESS Score

Query this with the API

The same record, from the CLI:

vulnetix vdb vuln CVE-2021-21409
vulnetix vdb fixes CVE-2021-21409

Or with curl, using the org id and key from your account page:

curl -s -H "Authorization: ApiKey ${VULNETIX_ORG_ID}:${VULNETIX_API_KEY}" \
  "https://api.vdb.vulnetix.com/v2/vuln/CVE-2021-21409/fixes/registry"

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References

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