# CVE-2021-35331: Code injection in n/a

> A format string vulnerability in Tcl's nmakehlp.c allows code execution via a crafted file, though its significance is disputed.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 5 Jul 2021
- **Updated:** 4 Aug 2024
- **Also known as:** DEBIAN-CVE-2021-35331, ECHO-cd9d-2394-e10e, GHSA-539q-24vg-qfm4, OESA-2022-1720, ROOT-OS-DEBIAN-12-CVE-2021-35331, SUSE-FU-2022:0484-1, SUSE-FU-2022:0868-1

## What is CVE-2021-35331?

CVE-2021-35331 is a high-severity code injection vulnerability in n/a, published on 5 Jul 2021. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

In Tcl 8.6.11, a format string vulnerability in nmakehlp.c might allow code execution via a crafted file. NOTE: multiple third parties dispute the significance of this finding

Weakness: CWE-134 (Use of Externally-Controlled Format String)

## Which versions are affected by CVE-2021-35331?

It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `tcl` | SUSE:Linux Enterprise Module for Basesystem 15 SP3 | All versions | 8.6.12-150300.14.3.1 |
| `tk` | SUSE:Linux Enterprise Module for Basesystem 15 SP3 | All versions | 8.6.12-150300.10.3.1 |
| `tk` | SUSE:Linux Enterprise Module for Desktop Applications 15 SP3 | All versions | 8.6.12-150300.10.3.1 |
| `tcl` | SUSE:Linux Enterprise Server 12 SP5 | All versions | 8.6.12-11.3.1 |
| `tk` | SUSE:Linux Enterprise Server 12 SP5 | All versions | 8.6.12-11.3.1 |
| `tcl` | SUSE:Linux Enterprise Server for SAP Applications 12 SP5 | All versions | 8.6.12-11.3.1 |
| `tk` | SUSE:Linux Enterprise Server for SAP Applications 12 SP5 | All versions | 8.6.12-11.3.1 |
| `tcl` | SUSE:Linux Enterprise Software Development Kit 12 SP5 | All versions | 8.6.12-11.3.1 |
| `tk` | SUSE:Linux Enterprise Software Development Kit 12 SP5 | All versions | 8.6.12-11.3.1 |

Products: Tcl Tcl.

## How do I fix CVE-2021-35331?

Apply the vendor's patch.

## Is CVE-2021-35331 being exploited?

There is no known exploitation of CVE-2021-35331 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-35331 and fix it if it is affected.

What it is: CVE-2021-35331 is a high-severity code injection vulnerability in n/a, published on 5 Jul 2021. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2021-35331 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-2021-35331/ (Markdown: https://insights.sbomify.com/CVE-2021-35331/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-35331
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-35331
- OSV: https://osv.dev/vulnerability/CVE-2021-35331

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-35331/
Summaries are generated and may contain mistakes; the official description above is the record.