# CVE-2020-11612: Denial of Service in Netty > An attacker can cause a denial of service by sending a large ZlibEncoded stream, forcing the Netty server to exhaust all available memory. - **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 7 Apr 2020 - **Updated:** 4 Aug 2024 - **Also known as:** CLEANSTART-2026-TF61372, CVE-2020-10707, DEBIAN-CVE-2020-11612, GHSA-mm9x-g8pc-w292, RHSA-2020:2605, UBUNTU-CVE-2020-11612 ## What is CVE-2020-11612? CVE-2020-11612 is a high-severity denial of service vulnerability in Debian Debian Linux, published on 7 Apr 2020. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official description The ZlibDecoders in Netty 4.1.x before 4.1.46 allow for unbounded memory allocation while decoding a ZlibEncoded byte stream. An attacker could send a large ZlibEncoded byte stream to the Netty server, forcing the server to allocate all of its free memory to a single decoder. Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling) ## Which versions are affected by CVE-2020-11612? 2 open source packages ship an affected version, including io.netty:netty-handler. It affects 13 products. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `io.netty:netty-handler` | Maven | From 4.1.0 | 4.1.46 | | `io.netty:netty-handler` | Maven | From 4.1.0 | 4.1.46 | | `python-qpid-proton` | Red Hat:a_mq_clients:2::el6 | All versions | 0:0.31.0-3.el6_10 | | `python-qpid-proton-docs` | Red Hat:a_mq_clients:2::el6 | All versions | 0:0.31.0-3.el6_10 | | `qpid-cpp` | Red Hat:a_mq_clients:2::el6 | All versions | 0:1.36.0-30.el6_10amq | | `qpid-cpp-client` | Red Hat:a_mq_clients:2::el6 | All versions | 0:1.36.0-30.el6_10amq | | `qpid-cpp-client-devel` | Red Hat:a_mq_clients:2::el6 | All versions | 0:1.36.0-30.el6_10amq | | `qpid-cpp-client-docs` | Red Hat:a_mq_clients:2::el6 | All versions | 0:1.36.0-30.el6_10amq | | `qpid-cpp-debuginfo` | Red Hat:a_mq_clients:2::el6 | All versions | 0:1.36.0-30.el6_10amq | | `qpid-proton` | Red Hat:a_mq_clients:2::el6 | All versions | 0:0.31.0-3.el6_10 | | `qpid-proton-c` | Red Hat:a_mq_clients:2::el6 | All versions | 0:0.31.0-3.el6_10 | | `qpid-proton-c-devel` | Red Hat:a_mq_clients:2::el6 | All versions | 0:0.31.0-3.el6_10 | | `qpid-proton-c-docs` | Red Hat:a_mq_clients:2::el6 | All versions | 0:0.31.0-3.el6_10 | | `qpid-proton-cpp` | Red Hat:a_mq_clients:2::el6 | All versions | 0:0.31.0-3.el6_10 | | `qpid-proton-cpp-devel` | Red Hat:a_mq_clients:2::el6 | All versions | 0:0.31.0-3.el6_10 | | `qpid-proton-cpp-docs` | Red Hat:a_mq_clients:2::el6 | All versions | 0:0.31.0-3.el6_10 | | `qpid-proton-debuginfo` | Red Hat:a_mq_clients:2::el6 | All versions | 0:0.31.0-3.el6_10 | | `qpid-proton-tests` | Red Hat:a_mq_clients:2::el6 | All versions | 0:0.31.0-3.el6_10 | | `python-qpid-proton` | Red Hat:a_mq_clients:2::el7 | All versions | 0:0.31.0-3.el7 | | `python-qpid-proton-docs` | Red Hat:a_mq_clients:2::el7 | All versions | 0:0.31.0-3.el7 | | `qpid-cpp` | Red Hat:a_mq_clients:2::el7 | All versions | 0:1.36.0-30.el7amq | | `qpid-cpp-client` | Red Hat:a_mq_clients:2::el7 | All versions | 0:1.36.0-30.el7amq | | `qpid-cpp-client-devel` | Red Hat:a_mq_clients:2::el7 | All versions | 0:1.36.0-30.el7amq | | `qpid-cpp-client-docs` | Red Hat:a_mq_clients:2::el7 | All versions | 0:1.36.0-30.el7amq | | `qpid-cpp-debuginfo` | Red Hat:a_mq_clients:2::el7 | All versions | 0:1.36.0-30.el7amq | | `qpid-proton` | Red Hat:a_mq_clients:2::el7 | All versions | 0:0.31.0-3.el7 | | `qpid-proton-c` | Red Hat:a_mq_clients:2::el7 | All versions | 0:0.31.0-3.el7 | | `qpid-proton-c-devel` | Red Hat:a_mq_clients:2::el7 | All versions | 0:0.31.0-3.el7 | | `qpid-proton-c-docs` | Red Hat:a_mq_clients:2::el7 | All versions | 0:0.31.0-3.el7 | | `qpid-proton-cpp` | Red Hat:a_mq_clients:2::el7 | All versions | 0:0.31.0-3.el7 | | `qpid-proton-cpp-devel` | Red Hat:a_mq_clients:2::el7 | All versions | 0:0.31.0-3.el7 | | `qpid-proton-cpp-docs` | Red Hat:a_mq_clients:2::el7 | All versions | 0:0.31.0-3.el7 | | `qpid-proton-debuginfo` | Red Hat:a_mq_clients:2::el7 | All versions | 0:0.31.0-3.el7 | | `qpid-proton-tests` | Red Hat:a_mq_clients:2::el7 | All versions | 0:0.31.0-3.el7 | | `rubygem-qpid_proton` | Red Hat:a_mq_clients:2::el7 | All versions | 0:0.31.0-2.el7 | | `rubygem-qpid_proton-debuginfo` | Red Hat:a_mq_clients:2::el7 | All versions | 0:0.31.0-2.el7 | | `nodejs-rhea` | Red Hat:a_mq_clients:2::el8 | All versions | 0:1.0.21-1.el8 | | `python-qpid-proton-docs` | Red Hat:a_mq_clients:2::el8 | All versions | 0:0.31.0-3.el8 | | `python3-qpid-proton` | Red Hat:a_mq_clients:2::el8 | All versions | 0:0.31.0-3.el8 | | `python3-qpid-proton-debuginfo` | Red Hat:a_mq_clients:2::el8 | All versions | 0:0.31.0-3.el8 | Products: Debian Debian Linux, Fedoraproject Fedora, Netapp Oncommand Api Services, Netapp Oncommand Insight, Netapp Oncommand Workflow Automation, Netty Netty, Oracle Communications Brm - Elastic Charging Engine, Oracle Communications Cloud Native Core Service Communication Proxy, Oracle Communications Design Studio, Oracle Communications Messaging Server, Oracle Nosql Database, Oracle Siebel Core - Server Framework, Oracle Webcenter Portal. ## How do I fix CVE-2020-11612? Upgrade io.netty:netty-handler to 4.1.46 or later. ## Is CVE-2020-11612 being exploited? There is no known exploitation of CVE-2020-11612 in the wild and no public exploit code. ## Other vulnerabilities in Debian Debian Linux - [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild) - [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild) - [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild) - [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild) - [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2020-11612 and fix it if it is affected. What it is: CVE-2020-11612 is a high-severity denial of service vulnerability in Debian Debian Linux, published on 7 Apr 2020. An attacker can exploit it over the internet without logging in, with no action from the victim. Exploitation: There is no known exploitation of CVE-2020-11612 in the wild and no public exploit code. Affected packages and fixed versions: - io.netty:netty-handler (Maven): affected from 4.1.0; fixed in 4.1.46 - io.netty:netty-handler (Maven): affected from 4.1.0; fixed in 4.1.46 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2020-11612/ (Markdown: https://insights.sbomify.com/CVE-2020-11612/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2020-11612 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-11612 - OSV: https://osv.dev/vulnerability/CVE-2020-11612 --- From sbomify Insights: https://insights.sbomify.com/CVE-2020-11612/ Summaries are generated and may contain mistakes; the official description above is the record.