# CVE-2016-0751: actionpack is vulnerable to denial of service via a crafted HTTP Accept header

> Remote attackers can cause denial of service via memory consumption by sending crafted HTTP Accept headers to Ruby on Rails applications.

- **Severity:** High 7.5 (`CVSS:3.0/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:** 16 Feb 2016
- **Updated:** 5 Aug 2024
- **Also known as:** DEBIAN-CVE-2016-0751, GHSA-ffpv-c4hm-3x6v

## What is CVE-2016-0751?

CVE-2016-0751 is a high-severity denial of service vulnerability in Rubyonrails Rails, published on 16 Feb 2016. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

actionpack/lib/action_dispatch/http/mime_type.rb in Action Pack in Ruby on Rails before 3.2.22.1, 4.0.x and 4.1.x before 4.1.14.1, 4.2.x before 4.2.5.1, and 5.x before 5.0.0.beta1.1 does not properly restrict use of the MIME type cache, which allows remote attackers to cause a denial of service (memory consumption) via a crafted HTTP Accept header.

Weakness: CWE-399

## Which versions are affected by CVE-2016-0751?

6 open source packages ship an affected version, including actionpack. It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `actionpack` | RubyGems | All versions | 3.2.22.1 |
| `actionpack` | RubyGems | All versions | 3.2.22.1 |
| `actionpack` | RubyGems | From 4.0.0 | 4.1.14.1 |
| `actionpack` | RubyGems | From 4.0.0 | 4.1.14.1 |
| `actionpack` | RubyGems | From 4.2.0 | 4.2.5.1 |
| `actionpack` | RubyGems | From 4.2.0 | 4.2.5.1 |

Products: Rubyonrails Rails, Rubyonrails Ruby on Rails.

## How do I fix CVE-2016-0751?

Upgrade actionpack to a fixed version for your release line: 3.2.22.1, 4.1.14.1 or 4.2.5.1.

## Is CVE-2016-0751 being exploited?

There is no known exploitation of CVE-2016-0751 in the wild and no public exploit code.

## Other vulnerabilities in Rubyonrails Rails

- [CVE-2013-0277](https://insights.sbomify.com/CVE-2013-0277/): Active Record contains deserialization of arbitrary YAML (critical 10.0)
- [CVE-2017-17916](https://insights.sbomify.com/CVE-2017-17916/): SQL injection in n/a (high 8.1)
- [CVE-2017-17917](https://insights.sbomify.com/CVE-2017-17917/): SQL injection in n/a (high 8.1)
- [CVE-2026-33195](https://insights.sbomify.com/CVE-2026-33195/): Rails Active Storage has possible Path Traversal in DiskService (high 8.0)
- [CVE-2024-26142](https://insights.sbomify.com/CVE-2024-26142/): Rails possible ReDoS vulnerability in Accept header parsing in Action Dispatch (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2016-0751 and fix it if it is affected.

What it is: CVE-2016-0751 is a high-severity denial of service vulnerability in Rubyonrails Rails, published on 16 Feb 2016. 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-2016-0751 in the wild and no public exploit code.

Affected packages and fixed versions:
- actionpack (RubyGems): affected all versions; fixed in 3.2.22.1
- actionpack (RubyGems): affected all versions; fixed in 3.2.22.1
- actionpack (RubyGems): affected from 4.0.0; fixed in 4.1.14.1
- actionpack (RubyGems): affected from 4.0.0; fixed in 4.1.14.1
- actionpack (RubyGems): affected from 4.2.0; fixed in 4.2.5.1
- actionpack (RubyGems): affected from 4.2.0; fixed in 4.2.5.1

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-2016-0751/ (Markdown: https://insights.sbomify.com/CVE-2016-0751/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2016-0751
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2016-0751
- OSV: https://osv.dev/vulnerability/CVE-2016-0751

---
From sbomify Insights: https://insights.sbomify.com/CVE-2016-0751/
Summaries are generated and may contain mistakes; the official description above is the record.