# CVE-2011-1521: Information disclosure in n/a

> Remote attackers can read local files or cause denial of service by tricking users into visiting URLs that redirect to local file paths.

- **Severity:** Medium 6.4 (`AV:N/AC:L/Au:N/C:P/I:N/A:P`)
- **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:** 24 May 2011
- **Updated:** 6 Aug 2024
- **Also known as:** DEBIAN-CVE-2011-1521, GHSA-cq22-fw8f-mvcw, PSF-2011-2

## What is CVE-2011-1521?

CVE-2011-1521 is a medium-severity vulnerability in Python Python, published on 24 May 2011. 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

The urllib and urllib2 modules in Python 2.x before 2.7.2 and 3.x before 3.2.1 process Location headers that specify redirection to file: URLs, which makes it easier for remote attackers to obtain sensitive information or cause a denial of service (resource consumption) via a crafted URL, as demonstrated by the file:///etc/passwd and file:///dev/zero URLs.

Weakness: CWE-399

## Which versions are affected by CVE-2011-1521?

It affects 1 product.


Products: Python Python.

## How do I fix CVE-2011-1521?

Upgrade to a fixed version.

## Is CVE-2011-1521 being exploited?

There is no known exploitation of CVE-2011-1521 in the wild and no public exploit code.

## 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-2011-1521 and fix it if it is affected.

What it is: CVE-2011-1521 is a medium-severity vulnerability in Python Python, published on 24 May 2011. 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-2011-1521 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-2011-1521/ (Markdown: https://insights.sbomify.com/CVE-2011-1521/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2011-1521
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2011-1521
- OSV: https://osv.dev/vulnerability/CVE-2011-1521

---
From sbomify Insights: https://insights.sbomify.com/CVE-2011-1521/
Summaries are generated and may contain mistakes; the official description above is the record.