CVE-2026-44892
HIGHCVE-2026-44892 is a high-severity (CVSS 7.5) vulnerability in io.netty:netty-codec-http3. O3 Security confirms whether CVE-2026-44892 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Netty has a Vulnerable Default Configuration Which Leads to Denial of Service via Unbounded HTTP/3 Header Size
Real-World Exposure
io.netty:netty-codec-http3Real-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. Prior to version 4.2.15.Final, the default configuration of the Http3ConnectionHandler in the Netty HTTP/3 codec lacks an enforced maximum header size limit. When a peer does not explicitly specify HTTP3_SETTINGS_MAX_FIELD_SECTION_SIZE, the implementation defaults to an unbounded limit. This insecure default configuration allows a malicious client or server to send an enormous number of headers, leading to a memory exhaustion Denial of Service via an OutOfMemoryError. Version 4.2.15.Final contains a patch.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | io.netty:netty-codec-http3 | ≥ 4.2.0.Final&&< 4.2.15.Final | 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-http3. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update io.netty:netty-codec-http3 to 4.2.15.Final or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-44892 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 pinpoints whether CVE-2026-44892 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-44892. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-44892 in your dependencies?
O3 detects CVE-2026-44892 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.