# CVE-2016-5699: Other in n/a

> Remote attackers can inject arbitrary HTTP headers via CRLF sequences in URLs using Python's urllib, potentially bypassing security controls.

- **Severity:** Medium 6.1 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 2 Sep 2016
- **Updated:** 6 Aug 2024
- **Also known as:** AZL-109611, DEBIAN-CVE-2016-5699, GHSA-mfrc-633m-gcwg, PSF-2016-8, UBUNTU-CVE-2016-5699

## What is CVE-2016-5699?

CVE-2016-5699 is a medium-severity vulnerability in Python Python, published on 2 Sep 2016. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

CRLF injection vulnerability in the HTTPConnection.putheader function in urllib2 and urllib in CPython (aka Python) before 2.7.10 and 3.x before 3.4.4 allows remote attackers to inject arbitrary HTTP headers via CRLF sequences in a URL.

Weakness: CWE-113 (Improper Neutralization of CRLF Sequences in HTTP Headers)

## Which versions are affected by CVE-2016-5699?

It affects 1 product.


Products: Python Python.

## How do I fix CVE-2016-5699?

Upgrade to a fixed version.

## Is CVE-2016-5699 being exploited?

There is no known exploitation of CVE-2016-5699 in the wild and no public exploit code.

Public exploit code:

- PoC code of CVE-2016-5699 Vulnerability (github_poc): https://github.com/bunseokbot/CVE-2016-5699-poc
- Reading Course Report (github_poc): https://github.com/shajinzheng/cve-2016-5699-jinzheng-sha

## Other vulnerabilities in Python Python

- [CVE-2008-5031](https://insights.sbomify.com/CVE-2008-5031/): Integer overflow in n/a (critical 10.0)
- [CVE-2014-4650](https://insights.sbomify.com/CVE-2014-4650/): Path traversal in n/a (critical 9.8)
- [CVE-2016-5636](https://insights.sbomify.com/CVE-2016-5636/): Integer overflow in n/a (critical 9.8)
- [CVE-2007-4559](https://insights.sbomify.com/CVE-2007-4559/): Path traversal in n/a (critical 9.8)
- [CVE-2017-17522](https://insights.sbomify.com/CVE-2017-17522/): Command injection in n/a (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2016-5699 and fix it if it is affected.

What it is: CVE-2016-5699 is a medium-severity vulnerability in Python Python, published on 2 Sep 2016. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2016-5699 in the wild and no public exploit code.

Affected product: Python Python. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2016-5699/ (Markdown: https://insights.sbomify.com/CVE-2016-5699/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2016-5699
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2016-5699
- OSV: https://osv.dev/vulnerability/CVE-2016-5699

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From sbomify Insights: https://insights.sbomify.com/CVE-2016-5699/
Summaries are generated and may contain mistakes; the official description above is the record.