Netty is an asynchronous, event-driven network application framework. In versions prior to 4.1.132.Final and 4.2.10.Final, a remote user can trigger a Denial of Service (DoS) against a Netty HTTP/2 server by sending a flood of CONTINUATION frames. The server's lack of a limit on the number of CONTINUATION frames, combined with a bypass of existing size-based mitigations using zero-byte frames, allows an user to cause excessive CPU consumption with minimal bandwidth, rendering the server unresponsive. Versions 4.1.132.Final and 4.2.10.Final fix the issue.
CVE-2026-33871
HIGHNVD 7.57.5
EchelonGraph scoreLOW confidence
This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit-prediction score not yet available (the EPSS model rescores nightly; freshly-published CVEs typically appear within 48 hours). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
Triggered by: NVD CVSS baseline
Sources: nvd
7.5
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
- High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 1%CVSS: 7.5Exploit: NoneExposed: 0
A fix is available — apply it.
- CVSS v3
- 7.5
- EG Score
- 7.5(low)
- EPSS
- 62.4%
- KEV
- Not listed
Published
March 27, 2026
Last Modified
July 3, 2026
Advisory Details (10)
Auto-updated Jul 3, 2026Patch available. Sources: github, redhat.
redhat Patch Available
Affected: Red Hat Enterprise Linux 9. Red Hat Product Security has rated this update as having a security impact of Important. A Common
https://access.redhat.com/errata/RHSA-2026:18055redhat Patch Available
Affected: Red Hat Enterprise Linux 8. Red Hat Product Security has rated this update as having a security impact of Important. A Common
https://access.redhat.com/errata/RHSA-2026:18054redhat Patch Available
redhat Patch Available
redhat Patch Available
redhat Patch Available
redhat Patch Available
redhat Patch Available
redhat Patch Available
github Patch Available
HTTP/2 CONTINUATION Frame Flood Denial of Service · Advisory · netty/netty · GitHub
https://github.com/netty/netty/security/advisories/GHSA-w9fj-cfpg-grvvVendor Advisories for CVE-2026-33871(16)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
- RHSA-2026:34608Red Hat Product SecurityHigh
Red Hat Security Advisory: Streams for Apache Kafka 2.9.4 release and security update
- RHSA-2026:22619Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat Data Grid 8.6.1 security update
- RHSA-2026:17789Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat build of Cryostat 4.2.0: new RHEL 9 container image security update
- RHSA-2026:18054Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat JBoss Enterprise Application Platform 8.1.6 security update
- RHSA-2026:18055Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat JBoss Enterprise Application Platform 8.1.6 security update
- RHSA-2026:18059Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat JBoss Enterprise Application Platform 8.1.6 security update
- RHSA-2026:17668Red Hat Product SecurityCritical
Red Hat Security Advisory: Red Hat Build of Apache Camel 4.18.1 for Spring Boot release.
- RHSA-2026:14276Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat AMQ Broker 7.12.7 release and security update
- +8 more
Patch Availability(8)
| Vendor / Ecosystem | Fixed in / Patch | Released | Source |
|---|---|---|---|
| redhat | netty-codec-http2 | 2026-06-02 | redhat |
| redhat | cryostat/jfr-datasource-rhel9:4.2.0-9 | 2026-05-26 | redhat |
| redhat | eap8-netty-transport-native-epoll-0:4.1.132-1.Final_redhat_00001.1.el9eap | 2026-05-18 | redhat |
| redhat | netty-codec-http-4.1.100.Final.jar | 2026-05-18 | redhat |
| redhat | eap8-netty-transport-native-epoll-0:4.1.132-1.Final_redhat_00001.1.el8eap | 2026-05-18 | redhat |
| redhat | patch | 2026-05-04 | redhat |
| redhat | devspaces/server-rhel9:1776796445 | 2026-04-23 | redhat |
| redhat | rhoai/odh-modelmesh-rhel9:1776756834 | 2026-04-23 | redhat |
Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.
Affected Packages
(1 across 1 ecosystem)
Maven(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| io.netty:netty-codec-http2 | 4.1.0.Beta4 ... 4.1.99.Final (144 versions) | 4.1.132.Final | — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 8× in last 7d / 11× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-06 16:27 UTCEPSS rescore
- 2026-07-06 16:27 UTCEPSS rescore
- 2026-07-06 02:23 UTCEPSS rescore
- 2026-07-06 02:23 UTCEPSS rescore
- 2026-07-05 02:30 UTCEPSS rescore
- 2026-07-04 06:31 UTCEPSS rescore
- 2026-07-01 15:06 UTCEPSS rescore
- 2026-06-30 23:22 UTCEPSS rescore
- 2026-06-30 04:32 UTCEG score recompute
- 2026-06-30 04:32 UTCVendor advisory
- 2026-06-30 04:32 UTCNVD updatefirst tracked
Related CVEs(same vendor + same CWE)
Same vendor
10 shownredhat
Frequently asked(5)
What is CVE-2026-33871?
CVE-2026-33871 is a high vulnerability published on March 27, 2026. Netty is an asynchronous, event-driven network application framework. In versions prior to 4.1.132.Final and 4.2.10.Final, a remote user can trigger a Denial of Service (DoS) against a Netty HTTP/2 server by sending a flood of CONTINUATION frames. The server's lack of a limit on the number of…
When was CVE-2026-33871 disclosed?
CVE-2026-33871 was first published in the National Vulnerability Database on March 27, 2026, with the most recent update on July 3, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-33871 actively exploited?
CVE-2026-33871 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 62.4% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-33871?
CVE-2026-33871 has a CVSS v3 base score of 7.5 (NVD). The EG score is currently aggregating — additional source signals are being incorporated as they become available..
How do I remediate CVE-2026-33871?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-33871, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-33871
Is Your Infrastructure Affected by CVE-2026-33871?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.