---
title: "CVE-2026-67429: Flyto2 Core: Arbitrary file write via image.download (and other file-writing modules)"
url: https://erroneo.us/security/cve/CVE-2026-67429/
description: "CVE-2026-67429 (flyto-core (PyPI)): Flyto2 Core is an execution kernel for automation and AI-agent workflows. Prior to 2.26.6, image.download and related…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-07-29
date_modified: 2026-07-30
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-67429"
kev: false
cvss: 10
epss: 0.0077
license: All rights reserved. Quote with attribution and a link.
---

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

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.8% , percentile 55: FIRST’s model estimates a 0.8% chance of exploitation activity in the next 30 days, higher than 55% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes flyto-core (PyPI) < 2.26.7, fixed in 2.26.7 . Check your lockfile, including transitive dependencies.

## What it is

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 outputdir instead of validatepathwithenvconfig and its FLYTOSANDBOXDIR 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.

## Affected packages

- PyPI `flyto-core` < 2.26.7 → fixed: 2.26.7

## Affected products (CVE record)

- flytohub flyto-core: < 2.26.6

## Severity

- GitHub_M CVSS 3.1: 10 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:H`
- GitHub CVSS 3.1: 10.0 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.77% probability of exploitation activity in the next 30 days; percentile 55.

## Sources

- [GitHub Advisory GHSA-2956-977x-2w3r](https://github.com/advisories/GHSA-2956-977x-2w3r)
- [CVE.org record CVE-2026-67429](https://www.cve.org/CVERecord?id=CVE-2026-67429)
- [NVD entry CVE-2026-67429](https://nvd.nist.gov/vuln/detail/CVE-2026-67429)
- [github.com](https://github.com/flytohub/flyto-core/security/advisories/GHSA-2956-977x-2w3r)
- [github.com](https://github.com/flytohub/flyto-core/commit/d5f89d71303e3c1e6418d347c5c55fcd173cc8cc)
- [github.com](https://github.com/flytohub/flyto-core/releases/tag/v2.26.6)

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Source page: https://erroneo.us/security/cve/CVE-2026-67429/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt