# CVE-2020-7694: Log Injection

> Attackers can inject ANSI escape sequences into uvicorn logs via crafted URLs, polluting logs and potentially manipulating terminal emulators.

- **Severity:** Low 3.7 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N/E:P/RL:U/RC:C`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 27 Jul 2020
- **Updated:** 17 Sep 2024
- **Also known as:** DEBIAN-CVE-2020-7694, GHSA-33c7-2mpw-hg34, PYSEC-2020-150, SNYK-PYTHON-UVICORN-575560, UBUNTU-CVE-2020-7694

## What is CVE-2020-7694?

CVE-2020-7694 is a low-severity code injection vulnerability in uvicorn, published on 27 Jul 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

This affects all versions of package uvicorn. The request logger provided by the package is vulnerable to ASNI escape sequence injection. Whenever any HTTP request is received, the default behaviour of uvicorn is to log its details to either the console or a log file. When attackers request crafted URLs with percent-encoded escape sequences, the logging component will log the URL after it's been processed with urllib.parse.unquote, therefore converting any percent-encoded characters into their single-character equivalent, which can have special meaning in terminal emulators. By requesting URLs with crafted paths, attackers can: * Pollute uvicorn's access logs, therefore jeopardising the integrity of such files. * Use ANSI sequence codes to attempt to interact with the terminal emulator that's displaying the logs (either in real time or from a file).

Weakness: CWE-94 (Improper Control of Generation of Code), CWE-116 (Improper Encoding or Escaping of Output)

## Which versions are affected by CVE-2020-7694?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `uvicorn` | PyPI | All versions | 0.11.7 |
| `uvicorn` | PyPI | All versions | 0.11.7 |
| `uvicorn` | PyPI | All versions | 0.11.7 |

Products: Encode Uvicorn.

## How do I fix CVE-2020-7694?

Upgrade uvicorn to 0.11.7 or later.

## Is CVE-2020-7694 being exploited?

There is no known exploitation of CVE-2020-7694 in the wild and no public exploit code.

## Other vulnerabilities in uvicorn

- [CVE-2020-7695](https://insights.sbomify.com/CVE-2020-7695/): HTTP Response Splitting (medium 5.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-7694 and fix it if it is affected.

What it is: CVE-2020-7694 is a low-severity code injection vulnerability in uvicorn, published on 27 Jul 2020. 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-2020-7694 in the wild and no public exploit code.

Affected packages and fixed versions:
- uvicorn (PyPI): affected all versions; fixed in 0.11.7
- uvicorn (PyPI): affected all versions; fixed in 0.11.7
- uvicorn (PyPI): affected all versions; fixed in 0.11.7

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-2020-7694/ (Markdown: https://insights.sbomify.com/CVE-2020-7694/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-7694
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-7694
- OSV: https://osv.dev/vulnerability/CVE-2020-7694

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-7694/
Summaries are generated and may contain mistakes; the official description above is the record.