CVE-2026-48043 — netty-codec-http2
MEDIUMCVE-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
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-48043 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,156 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
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 |
Detection & 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
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-48043 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-48043. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
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…
| 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 for Quarkus 3.33.2.SP1 | netty-codec-http2 | 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 Quarkus 3.27.4.SP1 | netty-codec-http2 | RHSA-2026:26018 |
| Red Hat build of Quarkus 3.33.2.SP1 | netty-codec-http2 | RHSA-2026:26017 |
| Red Hat Data Grid 8.6.2 | netty-codec-http2 | RHSA-2026:41951 |
| Red Hat JBoss Enterprise Application Platform 7.4 ELS on RHEL 7 | eap7-activemq-artemis-0:2.16.0-22.redhat_00057.1.el7eap | RHSA-2026:53644 |
Frequently Asked Questions
Is CVE-2026-48043 in your dependencies?
O3 Security finds CVE-2026-48043 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.