# CVE-2024-27528: wasm3 pywasm3 out-of-bounds read in m3_exec.h

Source: https://junglewise.ai/threats/cve-2024-27528-wasm3-pywasm3-out-of-bounds-read-in-m3-exec-h  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2024-11-09. Updated: 2026-06-09  
License: CC BY 4.0 with a link back

CVE-2024-27528 · Severity: high · CVSS 8.4 · Published 2024-11-09

A vulnerability exists in pywasm3, a Python wrapper for the Wasm3 WebAssembly runtime. By processing a specially crafted WebAssembly (.wasm) file, the application may crash or allow for unauthorized code execution. This could lead to a total service outage or allow an attacker to gain control over the system running the library.

Technologies: [pywasm3 (PyPI)](https://junglewise.ai/threats/technologies/pywasm3). Vendors: [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2024-27528 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2024-27528 being exploited in the wild.

**How severe is CVE-2024-27528?** High severity, with a CVSS score of 8.4, published 9 November 2024.

**Which products and versions are affected?** pywasm3 (PyPI) <= 0.5.0, ECOSYSTEM:introduced=0,last_affected=0.5.0, ECOSYSTEM:introduced=0,last_affected=139076a.

**Is there a fix for CVE-2024-27528?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2024-27528 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2024-27528?** Check whether you run pywasm3 (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An out-of-bounds (invalid) memory read vulnerability exists in the Wasm3 interpreter (specifically version 139076a and pywasm3 <= 0.5.0). The flaw is located in the execution engine, specifically within the 'op_Select_i32_ssr' function in 'm3_exec.h'. An attacker can exploit this by providing a malformed WebAssembly file that triggers an invalid memory dereference during validation or execution. This can result in a segmentation fault (DoS) or potentially be leveraged for arbitrary code execution. While the CVSS vector indicates local access, the vulnerability is triggered by the content of the loaded WASM module.

## Affected products

- wasm3 pywasm3 <= 0.5.0
- wasm3 wasm3 139076a

## Identifiers

- CVE-2024-27528
- GHSA-mhg9-mm8c-c683
- PYSEC-2024-304

## Timeline

- 2024-02-19: disclosed: Issue reported on GitHub repository
- 2024-11-08: advisory: NVD published CVE-2024-27528
- 2024-11-09: advisory: GitHub Advisory published

## References

- [https://github.com/wasm3/wasm3/issues/463](https://github.com/wasm3/wasm3/issues/463)
- [https://gist.github.com/haruki3hhh/baa757c4af4fefb410d9c74d7a68152e](https://gist.github.com/haruki3hhh/baa757c4af4fefb410d9c74d7a68152e)
- [https://github.com/pypa/advisory-database/tree/main/vulns/pywasm3/PYSEC-2024-304.yaml](https://github.com/pypa/advisory-database/tree/main/vulns/pywasm3/PYSEC-2024-304.yaml)
- [https://github.com/wasm3/pywasm3/blob/main/wasm3/m3_exec.h](https://github.com/wasm3/pywasm3/blob/main/wasm3/m3_exec.h)

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