# CVE-2018-12247: Null dereference in n/a

> A NULL pointer dereference in mruby allows attackers to cause a denial of service via specific clone operations.

- **Severity:** High 7.5 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 12 Jun 2018
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-8j6c-c99j-fh4c, UBUNTU-CVE-2018-12247

## What is CVE-2018-12247?

CVE-2018-12247 is a high-severity vulnerability in n/a, published on 12 Jun 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An issue was discovered in mruby 1.4.1. There is a NULL pointer dereference in mrb_class, related to certain .clone usage, because mrb_obj_clone in kernel.c copies flags other than the MRB_FLAG_IS_FROZEN flag (e.g., the embedded flag).

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2018-12247?

It affects 1 product.


Products: Mruby Mruby.

## How do I fix CVE-2018-12247?

No fix has been published for CVE-2018-12247 yet. Limit exposure of the affected software until one is available.

## Is CVE-2018-12247 being exploited?

There is no known exploitation of CVE-2018-12247 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2020-6838](https://insights.sbomify.com/CVE-2020-6838/): Use after free in n/a (critical 9.8)
- [CVE-2020-6839](https://insights.sbomify.com/CVE-2020-6839/): Memory corruption in n/a (critical 9.8)
- [CVE-2020-6840](https://insights.sbomify.com/CVE-2020-6840/): Use after free in n/a (critical 9.8)
- [CVE-2018-10199](https://insights.sbomify.com/CVE-2018-10199/): Use after free in n/a (critical 9.8)
- [CVE-2022-1212](https://insights.sbomify.com/CVE-2022-1212/): Use-After-Free in str_escape in mruby/mruby in mruby/mruby (critical 9.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-12247 and fix it if it is affected.

What it is: CVE-2018-12247 is a high-severity vulnerability in n/a, published on 12 Jun 2018. 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-2018-12247 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-2018-12247/ (Markdown: https://insights.sbomify.com/CVE-2018-12247/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-12247
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-12247
- OSV: https://osv.dev/vulnerability/CVE-2018-12247

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-12247/
Summaries are generated and may contain mistakes; the official description above is the record.