# CVE-2017-20202: Web Developer for Chrome v0.4.9 Malicious Backdoor Supply Chain Compromise

> A malicious backdoor in the Web Developer Chrome extension enabled code execution, credential theft, and ad fraud via a supply chain compromise.

- **Severity:** Critical 9.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N`)
- **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:** No
- **Published:** 8 Oct 2025
- **Updated:** 14 Oct 2025
- **Also known as:** GHSA-vwvp-p3cc-rrj2

## What is CVE-2017-20202?

CVE-2017-20202 is a critical vulnerability in Web Developer for Chrome, published on 8 Oct 2025. 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

Web Developer for Chrome v0.4.9 contained malicious code that generated a domain via a DGA and fetched a remote script. The fetched script conditionally loaded follow-on modules that performed extensive ad substitution and malvertising, displayed fake “repair” alerts that redirected users to affiliate programs, and attempted to harvest credentials when users logged in. Injected components enumerate common banner sizes for substitution, replace third-party ad calls, and redirect victim traffic to affiliate landing pages. Potential impacts include user-level code execution in the browser context, large-scale ad fraud and traffic hijacking, credential theft, and exposure to additional payloads delivered by the actor. The compromise was reported on by the maintainer of Web Developer for Chrome on August 2, 2017 and remediated in v0.5.0.

Weakness: CWE-506 (Embedded Malicious Code)

## Which versions are affected by CVE-2017-20202?


## How do I fix CVE-2017-20202?

No fix has been published for CVE-2017-20202 yet. Limit exposure of the affected software until one is available.

## Is CVE-2017-20202 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2017-20202 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2017-20202 and fix it if it is affected.

What it is: CVE-2017-20202 is a critical vulnerability in Web Developer for Chrome, published on 8 Oct 2025. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2017-20202 exists.

Affected product: Web Developer for Chrome. 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-2017-20202/ (Markdown: https://insights.sbomify.com/CVE-2017-20202/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2017-20202
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2017-20202
- OSV: https://osv.dev/vulnerability/CVE-2017-20202

---
From sbomify Insights: https://insights.sbomify.com/CVE-2017-20202/
Summaries are generated and may contain mistakes; the official description above is the record.