# CVE-2018-1000030: Use after free in n/a

> Race condition in Python threading allows heap buffer overflow and use-after-free, potentially enabling code execution or privilege escalation in multi-threaded environments.

- **Severity:** Low 3.6 (`CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 8 Feb 2018
- **Updated:** 8 Oct 2026
- **Also known as:** AZL-109623, DEBIAN-CVE-2018-1000030, GHSA-rwj4-fxr5-gh64, PSF-2018-2, UBUNTU-CVE-2018-1000030

## What is CVE-2018-1000030?

CVE-2018-1000030 is a low-severity use after free vulnerability in Canonical Ubuntu Linux, published on 8 Feb 2018. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Python 2.7.14 is vulnerable to a Heap-Buffer-Overflow as well as a Heap-Use-After-Free. Python versions prior to 2.7.14 may also be vulnerable and it appears that Python 2.7.17 and prior may also be vulnerable however this has not been confirmed. The vulnerability lies when multiply threads are handling large amounts of data. In both cases there is essentially a race condition that occurs. For the Heap-Buffer-Overflow, Thread 2 is creating the size for a buffer, but Thread1 is already writing to the buffer without knowing how much to write. So when a large amount of data is being processed, it is very easy to cause memory corruption using a Heap-Buffer-Overflow. As for the Use-After-Free, Thread3->Malloc->Thread1->Free's->Thread2-Re-uses-Free'd Memory. The PSRT has stated that this is not a security vulnerability due to the fact that the attacker must be able to run code, however in some situations, such as function as a service, this vulnerability can potentially be used by an attacker to violate a trust boundary, as such the DWF feels this issue deserves a CVE.

Weakness: CWE-787 (Out-of-bounds Write), CWE-416 (Use After Free)

## Which versions are affected by CVE-2018-1000030?

It affects 2 products.


Products: Canonical Ubuntu Linux, Python Python.

## How do I fix CVE-2018-1000030?

Upgrade to a fixed version.

## Is CVE-2018-1000030 being exploited?

There is no known exploitation of CVE-2018-1000030 in the wild and no public exploit code.

Public exploit code:

- Python 2.7.14 race condition UAF proof-of-concept (github_poc): https://github.com/tylepr96/CVE-2018-1000030

## Other vulnerabilities in Canonical Ubuntu Linux

- [CVE-2020-11651](https://insights.sbomify.com/CVE-2020-11651/): SaltStack Salt Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2020-7247](https://insights.sbomify.com/CVE-2020-7247/): OpenSMTPD Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2019-16928](https://insights.sbomify.com/CVE-2019-16928/): Exim Out-of-bounds Write (critical 9.8, exploited in the wild)
- [CVE-2018-6789](https://insights.sbomify.com/CVE-2018-6789/): Exim Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2015-2590](https://insights.sbomify.com/CVE-2015-2590/): Oracle Java SE and Java SE Embedded Remote Code Execution (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-1000030 and fix it if it is affected.

What it is: CVE-2018-1000030 is a low-severity use after free vulnerability in Canonical Ubuntu Linux, published on 8 Feb 2018. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2018-1000030 in the wild and no public exploit code.

Affected product: Canonical Ubuntu 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-2018-1000030/ (Markdown: https://insights.sbomify.com/CVE-2018-1000030/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-1000030
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-1000030
- OSV: https://osv.dev/vulnerability/CVE-2018-1000030

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-1000030/
Summaries are generated and may contain mistakes; the official description above is the record.