# CVE-2026-8261: Squirrel heap buffer overflow in SQFunctionProto::Load

Source: https://junglewise.ai/threats/cve-2026-8261-squirrel-heap-buffer-overflow-in-sqfunctionproto-load  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-11. Updated: 2026-07-23  
License: CC BY 4.0 with a link back

CVE-2026-8261 · Severity: medium · CVSS 5.9 · Published 2026-05-11

Squirrel is a high-level imperative, object-oriented programming language designed to be lightweight for use in applications like video games. A vulnerability in how the language handles compiled bytecode files allows a specially crafted file to crash the application or potentially execute unauthorized code. This risk is present when an application using Squirrel loads untrusted script files from a local source.

Technologies: [Squirrel Project Squirrel](https://junglewise.ai/threats/technologies/squirrel). Vendors: [Squirrel Project](https://junglewise.ai/threats/vendors/squirrel-project).

## Quick answers

**Is CVE-2026-8261 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-8261 being exploited in the wild.

**How severe is CVE-2026-8261?** Medium severity, with a CVSS score of 5.9, published 11 May 2026.

**Which products and versions are affected?** Squirrel Project Squirrel up to 3.2.

**Is there a fix for CVE-2026-8261?** 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-2026-8261 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-8261?** Check whether you run Squirrel Project Squirrel 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

A heap-based buffer overflow exists in Squirrel up to version 3.2 within the SQFunctionProto::Load function in squirrel/sqobject.cpp. The vulnerability is caused by an integer overflow in the _FUNC_SIZE macro when calculating memory allocation sizes for bytecode components (specifically nlineinfos and ndefaultparams). On 64-bit systems, crafted values in a .cnut bytecode file can cause the macro to wrap, resulting in a small memory allocation. Subsequent calls to SafeRead then perform a large write into this undersized buffer. An attacker can trigger this by providing a malicious bytecode file to any application using sqstd_loadfile or sq_readclosure. As of the advisory date, the project has not yet released a formal patch.

## Affected products

- Squirrel Project Squirrel up to 3.2

## Timeline

- 2026-04-22: disclosed: Issue reported on GitHub with PoC
- 2026-05-11: advisory: NVD publication date

## References

- [https://github.com/albertodemichelis/squirrel/issues/326](https://github.com/albertodemichelis/squirrel/issues/326)
- [https://github.com/biniamf/pocs/tree/main/squirrel-sqobject-functionproto-load-intovf-lineinfos](https://github.com/biniamf/pocs/tree/main/squirrel-sqobject-functionproto-load-intovf-lineinfos)
- [https://vuldb.com/submit/809904](https://vuldb.com/submit/809904)
- [https://vuldb.com/vuln/362558](https://vuldb.com/vuln/362558)
- [https://vuldb.com/vuln/362558/cti](https://vuldb.com/vuln/362558/cti)

## Related threats

- [Squirrel stack overflow in validate_format function](https://junglewise.ai/threats/cve-2026-8258-squirrel-stack-overflow-in-validate-format-function)