# CVE-2021-33477: Code injection in n/a

> Attackers can execute arbitrary code via malicious escape sequences in vulnerable terminal emulators like rxvt-unicode and Eterm.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 20 May 2021
- **Updated:** 3 Aug 2024
- **Also known as:** ALPINE-CVE-2021-33477, DEBIAN-CVE-2021-33477, DLA-2671-1, DLA-2681-1, DLA-2682-1, GHSA-vm2c-wqqr-v3gc, MGASA-2021-0358, UBUNTU-CVE-2021-33477, openSUSE-SU-2024:12386-1

## What is CVE-2021-33477?

CVE-2021-33477 is a high-severity code injection vulnerability in Debian Debian Linux, published on 20 May 2021. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

rxvt-unicode 9.22, rxvt 2.7.10, mrxvt 0.5.4, and Eterm 0.9.7 allow (potentially remote) code execution because of improper handling of certain escape sequences (ESC G Q). A response is terminated by a newline.

Weakness: CWE-755 (Improper Handling of Exceptional Conditions)

## Which versions are affected by CVE-2021-33477?

It affects 6 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `rxvt-unicode` | openSUSE:Tumbleweed | All versions | 9.30-2.1 |

Products: Debian Debian Linux, Eterm Project Eterm, Fedoraproject Fedora, Mrxvt Project Mrxvt, Rxvt-Unicode Project Rxvt-Unicode, Rxvt Project Rxvt.

## How do I fix CVE-2021-33477?

Apply the vendor's patch.

## Is CVE-2021-33477 being exploited?

There is no known exploitation of CVE-2021-33477 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-33477 and fix it if it is affected.

What it is: CVE-2021-33477 is a high-severity code injection vulnerability in Debian Debian Linux, published on 20 May 2021. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-33477 in the wild and no public exploit code.

Affected product: Debian Debian Linux. 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-2021-33477/ (Markdown: https://insights.sbomify.com/CVE-2021-33477/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-33477
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-33477
- OSV: https://osv.dev/vulnerability/CVE-2021-33477

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-33477/
Summaries are generated and may contain mistakes; the official description above is the record.