# CVE-2025-6272: wasm3 m3_compile.c MarkSlotAllocated out-of-bounds write

> A local attacker can trigger an out-of-bounds write in the wasm3 library, potentially leading to code execution or denial of service.

- **Severity:** Medium 4.8 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P`)
- **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:** 19 Jun 2025
- **Updated:** 23 Jun 2025
- **Also known as:** GHSA-rrmw-gv85-w824, PYSEC-2025-186

## What is CVE-2025-6272?

CVE-2025-6272 is a medium-severity memory corruption vulnerability in wasm3, published on 19 Jun 2025. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A vulnerability has been found in wasm3 0.5.0 and classified as problematic. This vulnerability affects the function MarkSlotAllocated of the file source/m3_compile.c. The manipulation leads to out-of-bounds write. An attack has to be approached locally. The exploit has been disclosed to the public and may be used.

Weakness: CWE-787 (Out-of-bounds Write), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2025-6272?

3 open source packages ship an affected version, including pywasm3. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `pywasm3` | PyPI | All versions to 0.5.0 | None |
| `pywasm3` | PyPI | All versions to 0.5.0 | None |
| `pywasm3` | PyPI | All versions to 0.5.0 | None |

Products: Wasm3 Project Wasm3.

## How do I fix CVE-2025-6272?

No fix has been published for CVE-2025-6272 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-6272 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-6272 exists.

## Other vulnerabilities in wasm3

- [CVE-2024-34249](https://insights.sbomify.com/CVE-2024-34249/): pywasm3 contains a heap buffer overflow which leads to segmentation fault (critical 9.8)
- [CVE-2024-27528](https://insights.sbomify.com/CVE-2024-27528/): pywasm3 has an Invalid Memory Read, Leading to DoS and Potential Code Execution (high 8.4)
- [CVE-2024-27529](https://insights.sbomify.com/CVE-2024-27529/): wasm3 uncontrolled memory allocation vulnerability (high 8.4)
- [CVE-2024-27530](https://insights.sbomify.com/CVE-2024-27530/): pywasm3 contains a Use-After-Free in ForEachModule (high 8.4)
- [CVE-2022-28990](https://insights.sbomify.com/CVE-2022-28990/): Buffer overflow in wasm3 (high 7.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-6272 and fix it if it is affected.

What it is: CVE-2025-6272 is a medium-severity memory corruption vulnerability in wasm3, published on 19 Jun 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-6272 exists.

Affected packages and fixed versions:
- pywasm3 (PyPI): affected all versions up to 0.5.0; no fix listed
- pywasm3 (PyPI): affected all versions up to 0.5.0; no fix listed
- pywasm3 (PyPI): affected all versions up to 0.5.0; 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-2025-6272/ (Markdown: https://insights.sbomify.com/CVE-2025-6272/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-6272
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-6272
- OSV: https://osv.dev/vulnerability/CVE-2025-6272

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-6272/
Summaries are generated and may contain mistakes; the official description above is the record.