CVE-2026-50560 is a medium-severity allocation of resources without limits or throttling vulnerability in io.netty:netty-codec-http2 (maven), affecting versions >= 4.2.0.Final, <= 4.2.14.Final. It is fixed in 4.2.15.Final, 4.1.135.Final.
Summary Netty HTTP/2 max header size handling produces attack similar to HTTP/2 Rapid Reset. Details There is a setting in the http2 specification called SETTINGSMAXHEADERLISTSIZE. According to the RFC: “This advisory setting informs a peer of the maximum field section size that the sender is prepared to accept, in units of octets.” When a client sends that setting to Netty, it appears that Netty will behave as follows: Read the request Proxy the request to the origin Attempt to produce a response Create an exception while writing the headers for the response Functionally, this should be similar to the http2 reset attack, but with a different on-the-wire signature. Remediation When speaking with clients, Netty should potentially treat this as “advisory” and ignore it. It would be best to ignore the SETTINGSMAXHEADERLISTSIZE setting from clients (or ignore it when sending to clients). According to the spec, a server does not need to honor this advisory setting, and it appears that other http/2 implementations ignore it when acting as a server. Impact This is a DDoS attack similar to the HTTP/2 Rapid Reset Attack. Credit Jonathan Looney (Engineering, Netflix) Contact Ashley Tolbert (Security, Netflix) - [email protected]
The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap. Typical impact: resource exhaustion leading to denial of service.
CVE-2026-50560 has a CVSS score of 5.3 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment.
A fixed version is available (4.2.15.Final, 4.1.135.Final). Upgrading removes the vulnerable code path.
maven
io.netty:netty-codec-http2 (>= 4.2.0.Final, <= 4.2.14.Final)io.netty:netty-codec-http2 (<= 4.1.134.Final)io.netty:netty-codec-http2 → 4.2.15.Final (maven)io.netty:netty-codec-http2 → 4.1.135.Final (maven)Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter instead of chasing every advisory.
Kodem's runtime-powered SCA identifies whether CVE-2026-50560 is reachable in your applications. Explore open-source security for your team.
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Upgrade the following packages to resolve this vulnerability:
io.netty:netty-codec-http2 to 4.2.15.Final or laterio.netty:netty-codec-http2 to 4.1.135.Final or laterKodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
CVE-2026-50560 is a medium-severity allocation of resources without limits or throttling vulnerability in io.netty:netty-codec-http2 (maven), affecting versions >= 4.2.0.Final, <= 4.2.14.Final. It is fixed in 4.2.15.Final, 4.1.135.Final. The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap.
CVE-2026-50560 has a CVSS score of 5.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
io.netty:netty-codec-http2 (maven) versions >= 4.2.0.Final, <= 4.2.14.Final is affected.
Yes. CVE-2026-50560 is fixed in 4.2.15.Final, 4.1.135.Final. Upgrade to this version or later.
Whether CVE-2026-50560 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
io.netty:netty-codec-http2 to 4.2.15.Final or laterio.netty:netty-codec-http2 to 4.1.135.Final or later