# CVE-2020-7767: Regular Expression Denial of Service (ReDoS)

> Attackers can cause denial of service in applications using express-validators by submitting crafted invalid URLs that trigger excessive regex processing.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/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:** No
- **Published:** 11 Nov 2020
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-cf2x-rqc8-grfq

## What is CVE-2020-7767?

CVE-2020-7767 is a medium-severity denial of service vulnerability in express-validators, published on 11 Nov 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

All versions of package express-validators are vulnerable to Regular Expression Denial of Service (ReDoS) when validating specifically-crafted invalid urls.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2020-7767?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `express-validators` | npm | All versions to 1.0.4 | None |
| `express-validators` | npm | All versions to 1.0.4 | None |

Products: Express-Validators Project Express-Validators.

## How do I fix CVE-2020-7767?

No fix has been published for CVE-2020-7767 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-7767 being exploited?

There is no known exploitation of CVE-2020-7767 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-7767 and fix it if it is affected.

What it is: CVE-2020-7767 is a medium-severity denial of service vulnerability in express-validators, published on 11 Nov 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-2020-7767 in the wild and no public exploit code.

Affected packages and fixed versions:
- express-validators (npm): affected all versions up to 1.0.4; no fix listed
- express-validators (npm): affected all versions up to 1.0.4; no fix listed

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-2020-7767/ (Markdown: https://insights.sbomify.com/CVE-2020-7767/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-7767
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-7767
- OSV: https://osv.dev/vulnerability/CVE-2020-7767

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-7767/
Summaries are generated and may contain mistakes; the official description above is the record.