# CVE-2021-25877: Code injection in n/a

> Administrators can execute arbitrary code via insecure file write in save.php, requiring immediate upgrade to secure versions.

- **Severity:** High 7.2 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 1 Nov 2021
- **Updated:** 9 Jul 2026
- **Also known as:** GHSA-mjww-cghr-9678

## What is CVE-2021-25877?

CVE-2021-25877 is a high-severity code injection vulnerability in n/a, published on 1 Nov 2021. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

AVideo/YouPHPTube 10.0 and prior is affected by Insecure file write. An administrator privileged user is able to write files on filesystem using flag and code variables in file save.php.

Weakness: CWE-94 (Improper Control of Generation of Code)

## Which versions are affected by CVE-2021-25877?

It affects 1 product.


Products: Youphptube Youphptube.

## How do I fix CVE-2021-25877?

No fix has been published for CVE-2021-25877 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-25877 being exploited?

There is no known exploitation of CVE-2021-25877 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2019-5151](https://insights.sbomify.com/CVE-2019-5151/): SQL injection in YouPHPTube (critical 10.0)
- [CVE-2019-18662](https://insights.sbomify.com/CVE-2019-18662/): SQL injection in n/a (critical 9.8)
- [CVE-2019-16124](https://insights.sbomify.com/CVE-2019-16124/): Missing authorization in n/a (critical 9.8)
- [CVE-2019-5150](https://insights.sbomify.com/CVE-2019-5150/): SQL injection in YouPHPTube (high 8.9)
- [CVE-2021-47749](https://insights.sbomify.com/CVE-2021-47749/): YouPHPTube <= 7.8 - Directory Traversal (high 8.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-25877 and fix it if it is affected.

What it is: CVE-2021-25877 is a high-severity code injection vulnerability in n/a, published on 1 Nov 2021. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-25877 in the wild and no public exploit code.

Affected product: n/a. 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-2021-25877/ (Markdown: https://insights.sbomify.com/CVE-2021-25877/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-25877
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-25877
- OSV: https://osv.dev/vulnerability/CVE-2021-25877

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-25877/
Summaries are generated and may contain mistakes; the official description above is the record.