What’s Vulnerable › Vulnerabilities

CVE-2026-44892: Netty has a Vulnerable Default Configuration Which Leads to Denial of Service via Unbounded HTTP/3 Header Size

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-12 · updated 2026-06-17
• Weakness: CWE-400

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 products

• netty: from 4.2.0 before 4.2.15 — fixed in 4.2.15

How to fix

Upgrade to a fixed version: netty 4.2.15. Check the vendor advisory for mitigations.

References

• https://github.com/netty/netty/releases/tag/netty-4.2.15.Final
• https://github.com/netty/netty/security/advisories/GHSA-c2rx-5r8w-8xr2

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