# CVE-2021-47955: CouchCMS 2.2.1 Cross-Site Scripting via SVG File Upload

> Authenticated attackers can execute arbitrary JavaScript in users' browsers by uploading malicious SVG files to CouchCMS.

- **Severity:** Medium 5.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/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:** 16 May 2026
- **Updated:** 24 May 2026
- **Also known as:** GHSA-7q3g-gccm-822q

## What is CVE-2021-47955?

CVE-2021-47955 is a medium-severity cross-site scripting vulnerability in CouchCMS, published on 16 May 2026. 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

CouchCMS 2.2.1 contains a cross-site scripting vulnerability that allows authenticated attackers to execute arbitrary JavaScript by uploading malicious SVG files through the file upload functionality. Attackers can upload SVG files containing embedded script tags to the browse.php endpoint, which are then executed in users' browsers when the files are accessed or previewed.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2021-47955?


## How do I fix CVE-2021-47955?

No fix has been published for CVE-2021-47955 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-47955 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-47955 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-47955 and fix it if it is affected.

What it is: CVE-2021-47955 is a medium-severity cross-site scripting vulnerability in CouchCMS, published on 16 May 2026. 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-2021-47955 exists.

Affected product: CouchCMS. 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-2021-47955/ (Markdown: https://insights.sbomify.com/CVE-2021-47955/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-47955
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-47955
- OSV: https://osv.dev/vulnerability/CVE-2021-47955

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-47955/
Summaries are generated and may contain mistakes; the official description above is the record.