# CVE-2016-6817: Improper Restriction of Operations within the Bounds of a Memory Buffer in Apache Tomcat

> An attacker can cause a denial of service in Apache Tomcat by sending an oversized HTTP/2 header, triggering an infinite loop in the parser.

- **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:** 10 Aug 2017
- **Updated:** 15 Oct 2024
- **Also known as:** GHSA-698c-2x4j-g9gq

## What is CVE-2016-6817?

CVE-2016-6817 is a high-severity denial of service vulnerability in Apache Tomcat, published on 10 Aug 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The HTTP/2 header parser in Apache Tomcat 9.0.0.M1 to 9.0.0.M11 and 8.5.0 to 8.5.6 entered an infinite loop if a header was received that was larger than the available buffer. This made a denial of service attack possible.

Weakness: CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer), CWE-835 (Loop with Unreachable Exit Condition)

## Which versions are affected by CVE-2016-6817?

4 open source packages ship an affected version, including org.apache.tomcat:tomcat. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `org.apache.tomcat:tomcat` | Maven | From 8.5.0 | 8.5.8 |
| `org.apache.tomcat:tomcat` | Maven | From 8.5.0 | 8.5.8 |
| `org.apache.tomcat:tomcat` | Maven | From 9.0.0.M1 | 9.0.0.M12 |
| `org.apache.tomcat:tomcat` | Maven | From 9.0.0.M1 | 9.0.0.M12 |

Products: Apache Tomcat.

## How do I fix CVE-2016-6817?

Upgrade org.apache.tomcat:tomcat to a fixed version for your release line: 8.5.8 or 9.0.0.M12.

## Is CVE-2016-6817 being exploited?

There is no known exploitation of CVE-2016-6817 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-2016-6817 and fix it if it is affected.

What it is: CVE-2016-6817 is a high-severity denial of service vulnerability in Apache Tomcat, published on 10 Aug 2017. 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-2016-6817 in the wild and no public exploit code.

Affected packages and fixed versions:
- org.apache.tomcat:tomcat (Maven): affected from 8.5.0; fixed in 8.5.8
- org.apache.tomcat:tomcat (Maven): affected from 8.5.0; fixed in 8.5.8
- org.apache.tomcat:tomcat (Maven): affected from 9.0.0.M1; fixed in 9.0.0.M12
- org.apache.tomcat:tomcat (Maven): affected from 9.0.0.M1; fixed in 9.0.0.M12

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-2016-6817/ (Markdown: https://insights.sbomify.com/CVE-2016-6817/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2016-6817
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2016-6817
- OSV: https://osv.dev/vulnerability/CVE-2016-6817

---
From sbomify Insights: https://insights.sbomify.com/CVE-2016-6817/
Summaries are generated and may contain mistakes; the official description above is the record.