# CVE-2018-1336: In Apache Tomcat there is an improper handing of overflow in the UTF-8 decoder > An attacker can cause a denial of service in Apache Tomcat by sending specially crafted UTF-8 supplementary characters that trigger an infinite loop in the decoder. - **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:** 2 Aug 2018 - **Updated:** 14 Nov 2024 - **Also known as:** GHSA-m59c-jpc8-m2x4, RHEA-2018:2188, RHEA-2018:2189, RHSA-2018:2701, RHSA-2018:2921, UBUNTU-CVE-2018-1336 ## What is CVE-2018-1336? CVE-2018-1336 is a high-severity denial of service vulnerability in Apache Tomcat, published on 2 Aug 2018. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official description An improper handing of overflow in the UTF-8 decoder with supplementary characters can lead to an infinite loop in the decoder causing a Denial of Service. Versions Affected: Apache Tomcat 9.0.0.M9 to 9.0.7, 8.5.0 to 8.5.30, 8.0.0.RC1 to 8.0.51, and 7.0.28 to 7.0.86. Weakness: CWE-835 (Loop with Unreachable Exit Condition) ## Which versions are affected by CVE-2018-1336? 8 open source packages ship an affected version, including org.apache.tomcat.embed:tomcat-embed-core. It affects 8 products. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `org.apache.tomcat.embed:tomcat-embed-core` | Maven | From 7.0.28 | 7.0.87 | | `org.apache.tomcat.embed:tomcat-embed-core` | Maven | From 7.0.28 | 7.0.87 | | `org.apache.tomcat.embed:tomcat-embed-core` | Maven | From 8.0.0RC1 | 8.0.51 | | `org.apache.tomcat.embed:tomcat-embed-core` | Maven | From 8.0.0RC1 | 8.0.51 | | `org.apache.tomcat.embed:tomcat-embed-core` | Maven | From 8.5.0 | 8.5.31 | | `org.apache.tomcat.embed:tomcat-embed-core` | Maven | From 8.5.0 | 8.5.31 | | `org.apache.tomcat.embed:tomcat-embed-core` | Maven | From 9.0.0.M9 | 9.0.8 | | `org.apache.tomcat.embed:tomcat-embed-core` | Maven | From 9.0.0.M9 | 9.0.8 | | `tomcat` | Red Hat:enterprise_linux:7::client | All versions | 0:7.0.76-8.el7_5 | | `tomcat-admin-webapps` | Red Hat:enterprise_linux:7::client | All versions | 0:7.0.76-8.el7_5 | | `tomcat-docs-webapp` | Red Hat:enterprise_linux:7::client | All versions | 0:7.0.76-8.el7_5 | | `tomcat-el-2.2-api` | Red Hat:enterprise_linux:7::client | All versions | 0:7.0.76-8.el7_5 | | `tomcat-javadoc` | Red Hat:enterprise_linux:7::client | All versions | 0:7.0.76-8.el7_5 | | `tomcat-jsp-2.2-api` | Red Hat:enterprise_linux:7::client | All versions | 0:7.0.76-8.el7_5 | | `tomcat-jsvc` | Red Hat:enterprise_linux:7::client | All versions | 0:7.0.76-8.el7_5 | | `tomcat-lib` | Red Hat:enterprise_linux:7::client | All versions | 0:7.0.76-8.el7_5 | | `tomcat-servlet-3.0-api` | Red Hat:enterprise_linux:7::client | All versions | 0:7.0.76-8.el7_5 | | `tomcat-webapps` | Red Hat:enterprise_linux:7::client | All versions | 0:7.0.76-8.el7_5 | | `tomcat` | Red Hat:enterprise_linux:7::computenode | All versions | 0:7.0.76-8.el7_5 | | `tomcat-admin-webapps` | Red Hat:enterprise_linux:7::computenode | All versions | 0:7.0.76-8.el7_5 | | `tomcat-docs-webapp` | Red Hat:enterprise_linux:7::computenode | All versions | 0:7.0.76-8.el7_5 | | `tomcat-el-2.2-api` | Red Hat:enterprise_linux:7::computenode | All versions | 0:7.0.76-8.el7_5 | | `tomcat-javadoc` | Red Hat:enterprise_linux:7::computenode | All versions | 0:7.0.76-8.el7_5 | | `tomcat-jsp-2.2-api` | Red Hat:enterprise_linux:7::computenode | All versions | 0:7.0.76-8.el7_5 | | `tomcat-jsvc` | Red Hat:enterprise_linux:7::computenode | All versions | 0:7.0.76-8.el7_5 | | `tomcat-lib` | Red Hat:enterprise_linux:7::computenode | All versions | 0:7.0.76-8.el7_5 | | `tomcat-servlet-3.0-api` | Red Hat:enterprise_linux:7::computenode | All versions | 0:7.0.76-8.el7_5 | | `tomcat-webapps` | Red Hat:enterprise_linux:7::computenode | All versions | 0:7.0.76-8.el7_5 | | `tomcat` | Red Hat:enterprise_linux:7::server | All versions | 0:7.0.76-8.el7_5 | | `tomcat-admin-webapps` | Red Hat:enterprise_linux:7::server | All versions | 0:7.0.76-8.el7_5 | | `tomcat-docs-webapp` | Red Hat:enterprise_linux:7::server | All versions | 0:7.0.76-8.el7_5 | | `tomcat-el-2.2-api` | Red Hat:enterprise_linux:7::server | All versions | 0:7.0.76-8.el7_5 | | `tomcat-javadoc` | Red Hat:enterprise_linux:7::server | All versions | 0:7.0.76-8.el7_5 | | `tomcat-jsp-2.2-api` | Red Hat:enterprise_linux:7::server | All versions | 0:7.0.76-8.el7_5 | | `tomcat-jsvc` | Red Hat:enterprise_linux:7::server | All versions | 0:7.0.76-8.el7_5 | | `tomcat-lib` | Red Hat:enterprise_linux:7::server | All versions | 0:7.0.76-8.el7_5 | | `tomcat-servlet-3.0-api` | Red Hat:enterprise_linux:7::server | All versions | 0:7.0.76-8.el7_5 | | `tomcat-webapps` | Red Hat:enterprise_linux:7::server | All versions | 0:7.0.76-8.el7_5 | | `tomcat` | Red Hat:enterprise_linux:7::workstation | All versions | 0:7.0.76-8.el7_5 | | `tomcat-admin-webapps` | Red Hat:enterprise_linux:7::workstation | All versions | 0:7.0.76-8.el7_5 | Products: Apache Tomcat, Canonical Ubuntu Linux, Debian Debian Linux, Redhat Enterprise Linux Desktop, Redhat Enterprise Linux Server, Redhat Enterprise Linux Workstation, Redhat Jboss Enterprise Application Platform, Redhat Jboss Enterprise Web Server. ## How do I fix CVE-2018-1336? Upgrade org.apache.tomcat.embed:tomcat-embed-core to a fixed version for your release line: 7.0.87, 8.0.51, 8.5.31 or 9.0.8. ## Is CVE-2018-1336 being exploited? There is no known exploitation of CVE-2018-1336 in the wild and no public exploit code. ## Other vulnerabilities in Apache Tomcat - [CVE-2025-24813](https://insights.sbomify.com/CVE-2025-24813/): Apache Tomcat Path Equivalence (critical 10.0, exploited in the wild) - [CVE-2016-8735](https://insights.sbomify.com/CVE-2016-8735/): Apache Tomcat Remote Code Execution (critical 9.8, exploited in the wild) - [CVE-2017-12617](https://insights.sbomify.com/CVE-2017-12617/): Apache Tomcat Remote Code Execution (high 8.1, exploited in the wild) - [CVE-2017-12615](https://insights.sbomify.com/CVE-2017-12615/): Apache Tomcat on Windows Remote Code Execution (high 8.1, exploited in the wild) - [CVE-2026-34486](https://insights.sbomify.com/CVE-2026-34486/): Apache Tomcat Missing Encryption of Sensitive Data (high 7.5, exploited in the wild) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2018-1336 and fix it if it is affected. What it is: CVE-2018-1336 is a high-severity denial of service vulnerability in Apache Tomcat, published on 2 Aug 2018. 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-2018-1336 in the wild and no public exploit code. Affected packages and fixed versions: - org.apache.tomcat.embed:tomcat-embed-core (Maven): affected from 7.0.28; fixed in 7.0.87 - org.apache.tomcat.embed:tomcat-embed-core (Maven): affected from 7.0.28; fixed in 7.0.87 - org.apache.tomcat.embed:tomcat-embed-core (Maven): affected from 8.0.0RC1; fixed in 8.0.51 - org.apache.tomcat.embed:tomcat-embed-core (Maven): affected from 8.0.0RC1; fixed in 8.0.51 - org.apache.tomcat.embed:tomcat-embed-core (Maven): affected from 8.5.0; fixed in 8.5.31 - org.apache.tomcat.embed:tomcat-embed-core (Maven): affected from 8.5.0; fixed in 8.5.31 - org.apache.tomcat.embed:tomcat-embed-core (Maven): affected from 9.0.0.M9; fixed in 9.0.8 - org.apache.tomcat.embed:tomcat-embed-core (Maven): affected from 9.0.0.M9; fixed in 9.0.8 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-2018-1336/ (Markdown: https://insights.sbomify.com/CVE-2018-1336/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2018-1336 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-1336 - OSV: https://osv.dev/vulnerability/CVE-2018-1336 --- From sbomify Insights: https://insights.sbomify.com/CVE-2018-1336/ Summaries are generated and may contain mistakes; the official description above is the record.