# CVE-2021-41170: Evaluation of closures can lead to execution of methods & functions in current program scope

> Attackers can execute arbitrary methods or functions in the current program scope by passing malicious closures to the template engine.

- **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:** 8 Nov 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-3v56-q6r6-4gcw

## What is CVE-2021-41170?

CVE-2021-41170 is a critical code injection vulnerability in sroehrl neoan3-template, published on 8 Nov 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

neoan3-apps/template is a neoan3 minimal template engine. Versions prior to 1.1.1 have allowed for passing in closures directly into the template engine. As a result values that are callable are executed by the template engine. The issue arises if a value has the same name as a method or function in scope and can therefore be executed either by mistake or maliciously. In theory all users of the package are affected as long as they either deal with direct user input or database values. A multi-step attack on is therefore plausible. Version 1.1.1 has addressed this vulnerability. Unfortunately only working with hardcoded values is safe in prior versions. As this likely defeats the purpose of a template engine, please upgrade.

Weakness: CWE-732 (Incorrect Permission Assignment for Critical Resource), CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component), CWE-277 (Insecure Inherited Permissions)

## Which versions are affected by CVE-2021-41170?

2 open source packages ship an affected version, including neoan3-apps/template. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `neoan3-apps/template` | Packagist | All versions | 1.1.1 |
| `neoan3-apps/template` | Packagist | All versions | 1.1.1 |

Products: Neoan Neoan3-Template.

## How do I fix CVE-2021-41170?

Upgrade neoan3-apps/template to 1.1.1 or later.

## Is CVE-2021-41170 being exploited?

There is no known exploitation of CVE-2021-41170 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-41170 and fix it if it is affected.

What it is: CVE-2021-41170 is a critical code injection vulnerability in sroehrl neoan3-template, published on 8 Nov 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-2021-41170 in the wild and no public exploit code.

Affected packages and fixed versions:
- neoan3-apps/template (Packagist): affected all versions; fixed in 1.1.1
- neoan3-apps/template (Packagist): affected all versions; fixed in 1.1.1

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-2021-41170/ (Markdown: https://insights.sbomify.com/CVE-2021-41170/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-41170
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-41170
- OSV: https://osv.dev/vulnerability/CVE-2021-41170

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-41170/
Summaries are generated and may contain mistakes; the official description above is the record.