# CVE-2020-28473: Web Cache Poisoning

> Attackers can poison web caches via parameter cloaking in the Bottle framework, causing malicious responses to be served to other users.

- **Severity:** Medium 6.8 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:H/E:P/RL:O/RC:C`)
- **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:** 18 Jan 2021
- **Updated:** 16 Sep 2024
- **Also known as:** DEBIAN-CVE-2020-28473, DLA-2531-1, GHSA-qhx9-7hx7-cp4r, MGASA-2021-0171, OESA-2021-1067, PYSEC-2021-129, SNYK-PYTHON-BOTTLE-1017108, SUSE-SU-2021:0483-1, UBUNTU-CVE-2020-28473, USN-5105-1, openSUSE-SU-2021:0302-1

## What is CVE-2020-28473?

CVE-2020-28473 is a medium-severity vulnerability in Debian Debian Linux, published on 18 Jan 2021. 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 package bottle from 0 and before 0.12.19 are vulnerable to Web Cache Poisoning by using a vector called parameter cloaking. When the attacker can separate query parameters using a semicolon (;), they can cause a difference in the interpretation of the request between the proxy (running with default configuration) and the server. This can result in malicious requests being cached as completely safe ones, as the proxy would usually not see the semicolon as a separator, and therefore would not include it in a cache key of an unkeyed parameter.

Weakness: CWE-444 (Inconsistent Interpretation of HTTP Requests)

## Which versions are affected by CVE-2020-28473?

3 open source packages ship an affected version, including bottle. It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `bottle` | PyPI | All versions | 0.12.19 |
| `bottle` | PyPI | All versions | 0.12.19 |
| `bottle` | PyPI | All versions | 0.12.19 |
| `python-bottle` | SUSE:Linux Enterprise Module for Desktop Applications 15 SP2 | All versions | 0.12.13-3.3.1 |
| `python-bottle` | SUSE:Linux Enterprise Module for Python 2 15 SP2 | All versions | 0.12.13-3.3.1 |
| `python-bottle` | openSUSE:Leap 15.2 | All versions | 0.12.13-lp152.4.3.1 |

Products: Bottlepy Bottle, Debian Debian Linux.

## How do I fix CVE-2020-28473?

Upgrade bottle to 0.12.19 or later.

## Is CVE-2020-28473 being exploited?

There is no known exploitation of CVE-2020-28473 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2022-31799](https://insights.sbomify.com/CVE-2022-31799/): Denial of service in bottle (critical 9.8)
- [CVE-2014-3137](https://insights.sbomify.com/CVE-2014-3137/): Bottle does not properly limit content-types (medium 6.8)
- [CVE-2016-9964](https://insights.sbomify.com/CVE-2016-9964/): bottle.py vulnerable to CRLF Injection (medium 6.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-28473 and fix it if it is affected.

What it is: CVE-2020-28473 is a medium-severity vulnerability in Debian Debian Linux, published on 18 Jan 2021. 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-2020-28473 in the wild and no public exploit code.

Affected packages and fixed versions:
- bottle (PyPI): affected all versions; fixed in 0.12.19
- bottle (PyPI): affected all versions; fixed in 0.12.19
- bottle (PyPI): affected all versions; fixed in 0.12.19

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-2020-28473/ (Markdown: https://insights.sbomify.com/CVE-2020-28473/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-28473
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-28473
- OSV: https://osv.dev/vulnerability/CVE-2020-28473

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-28473/
Summaries are generated and may contain mistakes; the official description above is the record.