# CVE-2023-7152: MicroPython modselect.c poll_set_add_fd use after free

> A use-after-free vulnerability in MicroPython's poll_set_add_fd function allows attackers to potentially execute arbitrary code or cause denial of service.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:L/I:L/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:** No
- **Published:** 29 Dec 2023
- **Updated:** 13 Feb 2025
- **Also known as:** GHSA-jpcc-65j8-6q37, PYSEC-2023-256, PYSEC-2023-257, PYSEC-2023-258, PYSEC-2023-259, UBUNTU-CVE-2023-7152

## What is CVE-2023-7152?

CVE-2023-7152 is a medium-severity use after free vulnerability in MicroPython, published on 29 Dec 2023. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A vulnerability, which was classified as critical, has been found in MicroPython 1.21.0/1.22.0-preview. Affected by this issue is the function poll_set_add_fd of the file extmod/modselect.c. The manipulation leads to use after free. The exploit has been disclosed to the public and may be used. The patch is identified as 8b24aa36ba978eafc6114b6798b47b7bfecdca26. It is recommended to apply a patch to fix this issue. VDB-249158 is the identifier assigned to this vulnerability.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2023-7152?

4 open source packages ship an affected version, including micropython-copy, micropython-io and micropython-os. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `micropython-copy` | PyPI | All versions | None |
| `micropython-io` | PyPI | All versions | None |
| `micropython-os` | PyPI | All versions | None |
| `micropython-select` | PyPI | All versions | None |

Products: Micropython Micropython.

## How do I fix CVE-2023-7152?

No fix has been published for CVE-2023-7152 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-7152 being exploited?

There is no known exploitation of CVE-2023-7152 in the wild and no public exploit code.

## Other vulnerabilities in MicroPython

- [CVE-2023-7158](https://insights.sbomify.com/CVE-2023-7158/): MicroPython objslice.c slice_indices heap-based overflow (high 7.3)
- [CVE-2024-8946](https://insights.sbomify.com/CVE-2024-8946/): MicroPython VFS Unmount vfs.c mp_vfs_umount heap-based overflow (medium 6.9)
- [CVE-2024-8948](https://insights.sbomify.com/CVE-2024-8948/): MicroPython objint.c mpz_as_bytes heap-based overflow (medium 6.9)
- [CVE-2024-8947](https://insights.sbomify.com/CVE-2024-8947/): MicroPython objarray.c use after free (medium 6.3)
- [CVE-2026-1998](https://insights.sbomify.com/CVE-2026-1998/): micropython runtime.c mp_import_all memory corruption (medium 4.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-7152 and fix it if it is affected.

What it is: CVE-2023-7152 is a medium-severity use after free vulnerability in MicroPython, published on 29 Dec 2023. 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-2023-7152 in the wild and no public exploit code.

Affected packages and fixed versions:
- micropython-copy (PyPI): affected all versions; no fix listed
- micropython-io (PyPI): affected all versions; no fix listed
- micropython-os (PyPI): affected all versions; no fix listed
- micropython-select (PyPI): affected all versions; no fix listed

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-2023-7152/ (Markdown: https://insights.sbomify.com/CVE-2023-7152/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-7152
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-7152
- OSV: https://osv.dev/vulnerability/CVE-2023-7152

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-7152/
Summaries are generated and may contain mistakes; the official description above is the record.