# CVE-2020-17527: Apache Tomcat: Request header mix-up between HTTP/2 streams > Apache Tomcat may leak request header information between HTTP/2 streams, potentially exposing sensitive data to attackers. - **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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:** 3 Dec 2020 - **Updated:** 8 Oct 2026 - **Also known as:** AZL-6909, AZL-7384, BIT-tomcat-2020-17527, DEBIAN-CVE-2020-17527, DLA-2495-1, GHSA-vvw4-rfwf-p6hx, MGASA-2021-0020, SUSE-SU-2021:0031-1, SUSE-SU-2021:0041-1, SUSE-SU-2021:0042-1, UBUNTU-CVE-2020-17527, openSUSE-SU-2021:0043-1, openSUSE-SU-2021:0081-1 ## What is CVE-2020-17527? CVE-2020-17527 is a high-severity vulnerability in Apache Tomcat, published on 3 Dec 2020. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official description While investigating bug 64830 it was discovered that Apache Tomcat 10.0.0-M1 to 10.0.0-M9, 9.0.0-M1 to 9.0.39 and 8.5.0 to 8.5.59 could re-use an HTTP request header value from the previous stream received on an HTTP/2 connection for the request associated with the subsequent stream. While this would most likely lead to an error and the closure of the HTTP/2 connection, it is possible that information could leak between requests. Weakness: CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor) ## Which versions are affected by CVE-2020-17527? 7 open source packages ship an affected version, including org.apache.tomcat:tomcat-coyote and tomcat. It affects 12 products. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `org.apache.tomcat:tomcat-coyote` | Maven | From 10.0.0-M1 | 10.0.0-M10 | | `org.apache.tomcat:tomcat-coyote` | Maven | From 10.0.0-M1 | 10.0.0-M10 | | `org.apache.tomcat:tomcat-coyote` | Maven | From 8.5.0 | 8.5.60 | | `org.apache.tomcat:tomcat-coyote` | Maven | From 8.5.0 | 8.5.60 | | `org.apache.tomcat:tomcat-coyote` | Maven | From 9.0.0-M1 | 9.0.40 | | `org.apache.tomcat:tomcat-coyote` | Maven | From 9.0.0-M1 | 9.0.40 | | `tomcat` | Bitnami | From 8.5.1 | 8.5.60, 9.0.40 | | `tomcat` | SUSE:Linux Enterprise Module for Web and Scripting 15 SP1 | All versions | 9.0.36-4.53.1 | | `tomcat` | SUSE:Linux Enterprise Module for Web and Scripting 15 SP2 | All versions | 9.0.36-3.18.1 | | `tomcat` | SUSE:Linux Enterprise Server 12 SP4-LTSS | All versions | 9.0.36-3.58.1 | | `tomcat` | SUSE:Linux Enterprise Server 12 SP5 | All versions | 9.0.36-3.58.1 | | `tomcat` | SUSE:Linux Enterprise Server for SAP Applications 12 SP4 | All versions | 9.0.36-3.58.1 | | `tomcat` | SUSE:Linux Enterprise Server for SAP Applications 12 SP5 | All versions | 9.0.36-3.58.1 | | `tomcat` | SUSE:OpenStack Cloud 9 | All versions | 9.0.36-3.58.1 | | `tomcat` | SUSE:OpenStack Cloud Crowbar 9 | All versions | 9.0.36-3.58.1 | | `tomcat` | openSUSE:Leap 15.1 | All versions | 9.0.36-lp151.3.39.1 | | `tomcat` | openSUSE:Leap 15.2 | All versions | 9.0.36-lp152.2.16.1 | Products: Apache Tomcat, Debian Debian Linux, Netapp Element Plug-In, Netapp Oncommand System Manager, Oracle Blockchain Platform, Oracle Communications Cloud Native Core Binding Support Function, Oracle Communications Cloud Native Core Policy, Oracle Communications Instant Messaging Server, Oracle Instantis Enterprisetrack, Oracle Mysql Enterprise Monitor, Oracle Sd-Wan Edge, Oracle Workload Manager. ## How do I fix CVE-2020-17527? Upgrade org.apache.tomcat:tomcat-coyote to a fixed version for your release line: 10.0.0-M10, 8.5.60 or 9.0.40. ## Is CVE-2020-17527 being exploited? There is no known exploitation of CVE-2020-17527 in the wild and no public exploit code. Public exploit code: - https://github.com/forse01/CVE-2020-17527-Tomcat (github_poc): https://github.com/forse01/CVE-2020-17527-Tomcat ## 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-2020-17527 and fix it if it is affected. What it is: CVE-2020-17527 is a high-severity vulnerability in Apache Tomcat, published on 3 Dec 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-2020-17527 in the wild and no public exploit code. Affected packages and fixed versions: - org.apache.tomcat:tomcat-coyote (Maven): affected from 10.0.0-M1; fixed in 10.0.0-M10 - org.apache.tomcat:tomcat-coyote (Maven): affected from 10.0.0-M1; fixed in 10.0.0-M10 - org.apache.tomcat:tomcat-coyote (Maven): affected from 8.5.0; fixed in 8.5.60 - org.apache.tomcat:tomcat-coyote (Maven): affected from 8.5.0; fixed in 8.5.60 - org.apache.tomcat:tomcat-coyote (Maven): affected from 9.0.0-M1; fixed in 9.0.40 - org.apache.tomcat:tomcat-coyote (Maven): affected from 9.0.0-M1; fixed in 9.0.40 - tomcat (Bitnami): affected from 8.5.1; fixed in 8.5.60, 9.0.40 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-2020-17527/ (Markdown: https://insights.sbomify.com/CVE-2020-17527/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2020-17527 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-17527 - OSV: https://osv.dev/vulnerability/CVE-2020-17527 --- From sbomify Insights: https://insights.sbomify.com/CVE-2020-17527/ Summaries are generated and may contain mistakes; the official description above is the record.