Prompty: Arbitrary file read via file reference expansion

## Summary Prompty loaders expanded `${file:...}` references in `.prompty` frontmatter without enforcing that the resolved path stayed within an authorized directory. An attacker-controlled prompt file could use path traversal or an absolute path to cause the host application to read files accessible to the process. ## Affected packages - PyPI `prompty` versions `<= 2.0.0b1`; fixed in `2.0.0b2` - npm `@prompty/core` versions `<= 2.0.0-beta.1`; fixed in `2.0.0-beta.2` - crates.io `prompty` versions `<= 2.0.0-beta.1`; fixed in `2.0.0-beta.2` - NuGet `Prompty.Core` versions `<= 2.0.0-beta.1`; fixed in `2.0.0-beta.2` ## Impact Applications that load untrusted `.prompty` files, user-provided prompt paths, or prompt bundles from less-trusted locations could disclose local files available to the application process when expanded values are logged, returned, or otherwise exposed. ## Remediation Upgrade to the fixed runtime version for your ecosystem. The fix makes file references secure by default: `${file:...}` may only resolve within the directory tree containing the `.prompty` file. Host applications that need shared prompt assets outside that tree must explicitly provide allowed file roots through runtime load options. Absolute paths, `..` traversal, and symlink escapes outside allowed roots are rejected. ## Fix details The patched runtimes canonicalize file-reference targets and allowed roots before reading referenced files, reject targets outside the prompt directory by default, and add regression coverage for traversal, absolute paths, explicit allowlists, and symlink escapes. The release commit is `88ac9948d7d37995edbb2f6d36913436626c39e1`.

Source published

17 Jul 2026 19:46:05 UTC

Source modified

31 Jul 2026 05:15:34 UTC

Observed here

23 Oct 2026 16:01:25 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Publisher rating · HIGH