# CVE-2021-41868: Remote unauthenticated attackers able to upload files in Onionshare

> Remote attackers can upload files to OnionShare receive nodes, potentially storing malicious content on the host system.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 4 Oct 2021
- **Updated:** 4 Aug 2024
- **Also known as:** DEBIAN-CVE-2021-41868, GHSA-7g47-xxff-9p85, PYSEC-2026-434, UBUNTU-CVE-2021-41868

## What is CVE-2021-41868?

CVE-2021-41868 is a critical vulnerability in n/a, published on 4 Oct 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

OnionShare 2.3 before 2.4 allows remote unauthenticated attackers to upload files on a non-public node when using the --receive functionality.

## Which versions are affected by CVE-2021-41868?

3 open source packages ship an affected version, including onionshare-cli. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `onionshare-cli` | PyPI | From 2.3 | 2.4 |
| `onionshare-cli` | PyPI | From 2.3 | 2.4 |
| `onionshare-cli` | PyPI | From 2.3 | 2.4 |

Products: Onionshare Onionshare.

## How do I fix CVE-2021-41868?

Upgrade onionshare-cli to 2.4 or later.

## Is CVE-2021-41868 being exploited?

There is no known exploitation of CVE-2021-41868 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2022-21690](https://insights.sbomify.com/CVE-2022-21690/): Cross-Site Scripting in Onionshare (high 8.7)
- [CVE-2022-21688](https://insights.sbomify.com/CVE-2022-21688/): Out-of-bounds Read in Onionshare (high 7.5)
- [CVE-2022-21689](https://insights.sbomify.com/CVE-2022-21689/): Denial of Service in Onionshare (high 7.5)
- [CVE-2018-19960](https://insights.sbomify.com/CVE-2018-19960/): Path traversal in n/a (high 7.0)
- [CVE-2022-21693](https://insights.sbomify.com/CVE-2022-21693/): Path traversal in Onionshare (medium 6.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-41868 and fix it if it is affected.

What it is: CVE-2021-41868 is a critical vulnerability in n/a, published on 4 Oct 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-2021-41868 in the wild and no public exploit code.

Affected packages and fixed versions:
- onionshare-cli (PyPI): affected from 2.3; fixed in 2.4
- onionshare-cli (PyPI): affected from 2.3; fixed in 2.4
- onionshare-cli (PyPI): affected from 2.3; fixed in 2.4

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-2021-41868/ (Markdown: https://insights.sbomify.com/CVE-2021-41868/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-41868
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-41868
- OSV: https://osv.dev/vulnerability/CVE-2021-41868

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-41868/
Summaries are generated and may contain mistakes; the official description above is the record.