Arbitrary file write in Flyto2 Core file-writing modules (CVE-2026-67429)

Flyto2 Core's `image.download` and related file-writing modules accept a caller-controlled `output_dir` parameter as the base path for path confinement checks instead of using the central `validate_path_with_env_config` guard and its `FLYTO_SANDBOX_DIR` restriction. Because the attacker controls both the target path and the base against which it is validated, the path check is bypassed, allowing attacker-controlled bytes from an HTTP response to be written to any filesystem path accessible to the process. Additional modules including `image.convert`, `image.resize`, `image.crop`, `image.compress`, `image.rotate`, `image.watermark`, `image.qrcode_generate`, `document.excel_write`, `document.pdf_fill_form`, `document.word_to_pdf`, `document.pdf_to_word`, and `browser.pagination` perform no path check at all, writing format-constrained content to a fully attacker-chosen path. Public POC available. Affected versions: - < 2.26.6 We recommend updating to: 2.26.6. CVSS 10.0 · our assessment: act_now Reference: https://github.com/flytohub/flyto-core/security/advisories/GHSA-2956-977x-2w3r Details: https://vuln.today/cve/CVE-2026-67429