# CVE-2020-1935: Potential HTTP request smuggling in Apache Tomcat > Attackers can perform HTTP request smuggling via invalid headers when Tomcat is behind a specific misconfigured reverse proxy. - **Severity:** Medium 4.8 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 24 Feb 2020 - **Updated:** 8 Oct 2026 - **Also known as:** BIT-tomcat-2020-1935, DEBIAN-CVE-2020-1935, GHSA-qxf4-chvg-4r8r, RHSA-2020:5020, UBUNTU-CVE-2020-1935 ## What is CVE-2020-1935? CVE-2020-1935 is a medium-severity vulnerability in Apache Tomcat, published on 24 Feb 2020. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official description In Apache Tomcat 9.0.0.M1 to 9.0.30, 8.5.0 to 8.5.50 and 7.0.0 to 7.0.99 the HTTP header parsing code used an approach to end-of-line parsing that allowed some invalid HTTP headers to be parsed as valid. This led to a possibility of HTTP Request Smuggling if Tomcat was located behind a reverse proxy that incorrectly handled the invalid Transfer-Encoding header in a particular manner. Such a reverse proxy is considered unlikely. Weakness: CWE-444 (Inconsistent Interpretation of HTTP Requests) ## Which versions are affected by CVE-2020-1935? 13 open source packages ship an affected version, including org.apache.tomcat.embed:tomcat-embed-core, tomcat and org.apache.tomcat:tomcat. It affects 20 products. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `org.apache.tomcat.embed:tomcat-embed-core` | Maven | All versions | 7.0.100 | | `org.apache.tomcat.embed:tomcat-embed-core` | Maven | All versions | 7.0.100 | | `org.apache.tomcat.embed:tomcat-embed-core` | Maven | From 8.0.0 | 8.5.51 | | `org.apache.tomcat.embed:tomcat-embed-core` | Maven | From 8.0.0 | 8.5.51 | | `org.apache.tomcat.embed:tomcat-embed-core` | Maven | From 9.0.0 | 9.0.31 | | `org.apache.tomcat.embed:tomcat-embed-core` | Maven | From 9.0.0 | 9.0.31 | | `tomcat` | Bitnami | From 7.0.0 | 7.0.100, 8.5.51, 9.0.31 | | `org.apache.tomcat:tomcat` | Maven | All versions | 7.0.100 | | `org.apache.tomcat:tomcat` | Maven | All versions | 7.0.100 | | `org.apache.tomcat:tomcat` | Maven | From 8.0.0 | 8.5.51 | | `org.apache.tomcat:tomcat` | Maven | From 8.0.0 | 8.5.51 | | `org.apache.tomcat:tomcat` | Maven | From 9.0.0 | 9.0.31 | | `org.apache.tomcat:tomcat` | Maven | From 9.0.0 | 9.0.31 | | `tomcat` | Red Hat:enterprise_linux:7::client | All versions | 0:7.0.76-16.el7_9 | | `tomcat-admin-webapps` | Red Hat:enterprise_linux:7::client | All versions | 0:7.0.76-16.el7_9 | | `tomcat-docs-webapp` | Red Hat:enterprise_linux:7::client | All versions | 0:7.0.76-16.el7_9 | | `tomcat-el-2.2-api` | Red Hat:enterprise_linux:7::client | All versions | 0:7.0.76-16.el7_9 | | `tomcat-javadoc` | Red Hat:enterprise_linux:7::client | All versions | 0:7.0.76-16.el7_9 | | `tomcat-jsp-2.2-api` | Red Hat:enterprise_linux:7::client | All versions | 0:7.0.76-16.el7_9 | | `tomcat-jsvc` | Red Hat:enterprise_linux:7::client | All versions | 0:7.0.76-16.el7_9 | | `tomcat-lib` | Red Hat:enterprise_linux:7::client | All versions | 0:7.0.76-16.el7_9 | | `tomcat-servlet-3.0-api` | Red Hat:enterprise_linux:7::client | All versions | 0:7.0.76-16.el7_9 | | `tomcat-webapps` | Red Hat:enterprise_linux:7::client | All versions | 0:7.0.76-16.el7_9 | | `tomcat` | Red Hat:enterprise_linux:7::computenode | All versions | 0:7.0.76-16.el7_9 | | `tomcat-admin-webapps` | Red Hat:enterprise_linux:7::computenode | All versions | 0:7.0.76-16.el7_9 | | `tomcat-docs-webapp` | Red Hat:enterprise_linux:7::computenode | All versions | 0:7.0.76-16.el7_9 | | `tomcat-el-2.2-api` | Red Hat:enterprise_linux:7::computenode | All versions | 0:7.0.76-16.el7_9 | | `tomcat-javadoc` | Red Hat:enterprise_linux:7::computenode | All versions | 0:7.0.76-16.el7_9 | | `tomcat-jsp-2.2-api` | Red Hat:enterprise_linux:7::computenode | All versions | 0:7.0.76-16.el7_9 | | `tomcat-jsvc` | Red Hat:enterprise_linux:7::computenode | All versions | 0:7.0.76-16.el7_9 | | `tomcat-lib` | Red Hat:enterprise_linux:7::computenode | All versions | 0:7.0.76-16.el7_9 | | `tomcat-webapps` | Red Hat:enterprise_linux:7::computenode | All versions | 0:7.0.76-16.el7_9 | | `tomcat` | Red Hat:enterprise_linux:7::server | All versions | 0:7.0.76-16.el7_9 | | `tomcat-admin-webapps` | Red Hat:enterprise_linux:7::server | All versions | 0:7.0.76-16.el7_9 | | `tomcat-docs-webapp` | Red Hat:enterprise_linux:7::server | All versions | 0:7.0.76-16.el7_9 | | `tomcat-el-2.2-api` | Red Hat:enterprise_linux:7::server | All versions | 0:7.0.76-16.el7_9 | | `tomcat-javadoc` | Red Hat:enterprise_linux:7::server | All versions | 0:7.0.76-16.el7_9 | | `tomcat-jsp-2.2-api` | Red Hat:enterprise_linux:7::server | All versions | 0:7.0.76-16.el7_9 | | `tomcat-jsvc` | Red Hat:enterprise_linux:7::server | All versions | 0:7.0.76-16.el7_9 | | `tomcat-lib` | Red Hat:enterprise_linux:7::server | All versions | 0:7.0.76-16.el7_9 | Products: Apache Tomcat, Canonical Ubuntu Linux, Debian Debian Linux, Netapp Data Availability Services, Netapp Oncommand System Manager, Opensuse Leap, Oracle Agile Engineering Data Management, Oracle Agile Product Lifecycle Management, Oracle Communications Element Manager, Oracle Communications Instant Messaging Server, Oracle Health Sciences Empirica Inspections, Oracle Health Sciences Empirica Signal, Oracle Hospitality Guest Access, Oracle Hyperion Infrastructure Technology, Oracle Instantis Enterprisetrack, Oracle Mysql Enterprise Monitor, Oracle Retail Order Broker, Oracle Siebel Ui Framework, Oracle Transportation Management, Oracle Workload Manager. ## How do I fix CVE-2020-1935? Upgrade org.apache.tomcat.embed:tomcat-embed-core to a fixed version for your release line: 7.0.100, 8.5.51 or 9.0.31. ## Is CVE-2020-1935 being exploited? There is no known exploitation of CVE-2020-1935 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-2020-1935 and fix it if it is affected. What it is: CVE-2020-1935 is a medium-severity vulnerability in Apache Tomcat, published on 24 Feb 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-2020-1935 in the wild and no public exploit code. Affected packages and fixed versions: - org.apache.tomcat.embed:tomcat-embed-core (Maven): affected all versions; fixed in 7.0.100 - org.apache.tomcat.embed:tomcat-embed-core (Maven): affected all versions; fixed in 7.0.100 - org.apache.tomcat.embed:tomcat-embed-core (Maven): affected from 8.0.0; fixed in 8.5.51 - org.apache.tomcat.embed:tomcat-embed-core (Maven): affected from 8.0.0; fixed in 8.5.51 - org.apache.tomcat.embed:tomcat-embed-core (Maven): affected from 9.0.0; fixed in 9.0.31 - org.apache.tomcat.embed:tomcat-embed-core (Maven): affected from 9.0.0; fixed in 9.0.31 - tomcat (Bitnami): affected from 7.0.0; fixed in 7.0.100, 8.5.51, 9.0.31 - org.apache.tomcat:tomcat (Maven): affected all versions; fixed in 7.0.100 - org.apache.tomcat:tomcat (Maven): affected all versions; fixed in 7.0.100 - org.apache.tomcat:tomcat (Maven): affected from 8.0.0; fixed in 8.5.51 - org.apache.tomcat:tomcat (Maven): affected from 8.0.0; fixed in 8.5.51 - org.apache.tomcat:tomcat (Maven): affected from 9.0.0; fixed in 9.0.31 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-2020-1935/ (Markdown: https://insights.sbomify.com/CVE-2020-1935/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2020-1935 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-1935 - OSV: https://osv.dev/vulnerability/CVE-2020-1935 --- From sbomify Insights: https://insights.sbomify.com/CVE-2020-1935/ Summaries are generated and may contain mistakes; the official description above is the record.