# CVE-2021-27515: Path traversal in url-parse

> Attackers can bypass URL validation checks by using backslashes, potentially leading to open redirects or security bypasses in applications using this library.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/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:** 21 Feb 2021
- **Updated:** 3 Aug 2024
- **Also known as:** DEBIAN-CVE-2021-27515, GHSA-9m6j-fcg5-2442, UBUNTU-CVE-2021-27515

## What is CVE-2021-27515?

CVE-2021-27515 is a medium-severity vulnerability in n/a, published on 21 Feb 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

url-parse before 1.5.0 mishandles certain uses of backslash such as http:\/ and interprets the URI as a relative path.

## Which versions are affected by CVE-2021-27515?

2 open source packages ship an affected version, including url-parse. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `url-parse` | npm | From 0.1.0 | 1.5.0 |
| `url-parse` | npm | From 0.1.0 | 1.5.0 |

Products: Url-Parse Project Url-Parse.

## How do I fix CVE-2021-27515?

Upgrade url-parse to 1.5.0 or later.

## Is CVE-2021-27515 being exploited?

There is no known exploitation of CVE-2021-27515 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2018-3774](https://insights.sbomify.com/CVE-2018-3774/): Open Redirect in url-parse (critical 10.0)
- [CVE-2022-0512](https://insights.sbomify.com/CVE-2022-0512/): Authorization Bypass Through User-Controlled Key in unshiftio/url-parse (high 8.8)
- [CVE-2022-0691](https://insights.sbomify.com/CVE-2022-0691/): Authorization Bypass Through User-Controlled Key in unshiftio/url-parse (medium 6.5)
- [CVE-2022-0686](https://insights.sbomify.com/CVE-2022-0686/): Authorization Bypass Through User-Controlled Key in unshiftio/url-parse (medium 6.5)
- [CVE-2022-0639](https://insights.sbomify.com/CVE-2022-0639/): Authorization Bypass Through User-Controlled Key in unshiftio/url-parse (medium 6.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-27515 and fix it if it is affected.

What it is: CVE-2021-27515 is a medium-severity vulnerability in n/a, published on 21 Feb 2021. 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-2021-27515 in the wild and no public exploit code.

Affected packages and fixed versions:
- url-parse (npm): affected from 0.1.0; fixed in 1.5.0
- url-parse (npm): affected from 0.1.0; fixed in 1.5.0

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-2021-27515/ (Markdown: https://insights.sbomify.com/CVE-2021-27515/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-27515
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-27515
- OSV: https://osv.dev/vulnerability/CVE-2021-27515

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-27515/
Summaries are generated and may contain mistakes; the official description above is the record.