# CVE-2012-2374: Tornado CRLF injection vulnerability

> Remote attackers can inject arbitrary HTTP headers and conduct response splitting attacks via crafted input in the Tornado web framework.

- **Severity:** Medium 5.0 (`AV:N/AC:L/Au:N/C:N/I:P/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:** 23 May 2012
- **Updated:** 6 Aug 2024
- **Also known as:** DEBIAN-CVE-2012-2374, GHSA-f7fv-v9rh-prvc, PYSEC-2012-5

## What is CVE-2012-2374?

CVE-2012-2374 is a medium-severity vulnerability in n/a, published on 23 May 2012. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

CRLF injection vulnerability in the tornado.web.RequestHandler.set_header function in Tornado before 2.2.1 allows remote attackers to inject arbitrary HTTP headers and conduct HTTP response splitting attacks via crafted input.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2012-2374?

3 open source packages ship an affected version, including tornado. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `tornado` | PyPI | All versions | 2.2.1 |
| `tornado` | PyPI | All versions | 2.2.1 |
| `tornado` | PyPI | All versions | 2.2.1 |

Products: Tornadoweb Tornado.

## How do I fix CVE-2012-2374?

Upgrade tornado to 2.2.1 or later.

## Is CVE-2012-2374 being exploited?

There is no known exploitation of CVE-2012-2374 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2026-31958](https://insights.sbomify.com/CVE-2026-31958/): Tornado has a DoS due to too many multipart parts (high 8.7)
- [CVE-2025-67725](https://insights.sbomify.com/CVE-2025-67725/): Tornado is Vulnerable to Quadratic DoS via Repeated Header Coalescing (high 7.5)
- [CVE-2025-67726](https://insights.sbomify.com/CVE-2025-67726/): Tornado is Vulnerable to Quadratic DoS via Crafted Multipart Parameters (high 7.5)
- [CVE-2024-52804](https://insights.sbomify.com/CVE-2024-52804/): Tornado has HTTP cookie parsing DoS vulnerability (high 7.5)
- [CVE-2026-35536](https://insights.sbomify.com/CVE-2026-35536/): Tornado has incomplete validation of cookie attributes (high 7.2)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2012-2374 and fix it if it is affected.

What it is: CVE-2012-2374 is a medium-severity vulnerability in n/a, published on 23 May 2012. 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-2012-2374 in the wild and no public exploit code.

Affected packages and fixed versions:
- tornado (PyPI): affected all versions; fixed in 2.2.1
- tornado (PyPI): affected all versions; fixed in 2.2.1
- tornado (PyPI): affected all versions; fixed in 2.2.1

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-2012-2374/ (Markdown: https://insights.sbomify.com/CVE-2012-2374/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2012-2374
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2012-2374
- OSV: https://osv.dev/vulnerability/CVE-2012-2374

---
From sbomify Insights: https://insights.sbomify.com/CVE-2012-2374/
Summaries are generated and may contain mistakes; the official description above is the record.