CVE-2026-48043 is a medium-severity (CVSS 5.3) Uncontrolled Resource Consumption vulnerability in io.netty:netty-codec-http2. A fix is available for io.netty:netty-codec-http2 — see the affected versions and patch details below.
netty-codec-http2: ByteBuf Reference-Count Leak in DelegatingDecompressorFrameListener Leads to Memory Exhaustion
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-48043.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
io.netty:netty-codec-http2☕io.netty:netty-codec-http2Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
Netty is a network application framework for development of protocol servers and clients. In netty-codec-http2 prior to versions 4.1.135.Final and 4.2.15.Final, the DelegatingDecompressorFrameListener class orchestrates HTTP/2 decompression by embedding a per-stream EmbeddedChannel that runs the appropriate decompression codec (gzip, deflate, zstd) and forwards decompressed chunks to a wrapped listener. Each decompressed chunk is a pooled ByteBuf handed to an anonymous ChannelInboundHandlerAdapter tail handler, which becomes the sole owner responsible for releasing it. A remote peer could send frames that would result in the flow-controller throwing and so trigger a resource leak which at the end might take down the whole JVM due OOME. Versions 4.1.135.Final and 4.2.15.Final patch the issue.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | io.netty:netty-codec-http2 | all versions | 4.1.135.Finalio.netty:netty-codec-http2:4.1.135.Final |
| ☕Maven | io.netty:netty-codec-http2 | ≥ 4.2.0.Alpha1&&< 4.2.15.Final | 4.2.15.Finalio.netty:netty-codec-http2:4.2.15.Final |
Affected Products
nettynettyDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.netty:netty-codec-http2, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update io.netty:netty-codec-http2 to 4.1.135.Final or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-48043 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
This is an Important denial of service flaw in netty-codec-http2, affecting Red Hat products that utilize HTTP/2 communication with decompression. A remote attacker can exploit a resource leak in the `DelegatingDecompressorFrameListener` by sending malformed HTTP/2 frames, potentially leading to an Out Of Memory Error…
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.Source: Red Hat security advisory for CVE-2026-48043 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Cryostat 4 on RHEL 9 | cryostat/cryostat-reports-rhel9:4.2.0-13 | RHSA-2026:48151 |
| Red Hat AMQ Broker 7.14.1 | netty-codec-http2 | RHSA-2026:66488 |
| Red Hat Build of Apache Camel 3.33.2.SP1 | io.netty/netty-codec-http2:4.1.135.Final-redhat-00001 | RHSA-2026:26586 |
| Red Hat build of Apache Camel 4.18.1.P1 for Spring Boot 3.5.16 | netty-codec-http2 | RHSA-2026:37390 |
| Red Hat build of Keycloak 26.4.13 | see advisory | RHSA-2026:30049 |
| Red Hat build of Keycloak 26.6.4 | see advisory | RHSA-2026:30083 |
| Red Hat build of Quarkus 3.27.4.SP1 | io.netty/netty-codec-http2:4.1.135.Final-redhat-00001 | RHSA-2026:26018 |
| Red Hat build of Quarkus 3.33.2.SP1 | io.netty/netty-codec-http2:4.1.135.Final-redhat-00001 | RHSA-2026:26017 |
Frequently Asked Questions
Is CVE-2026-48043 in your dependencies?
Find it across Maven, including transitive dependencies.