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CVE-2026-53951

CVE-2026-53951 · Copier: trust-prefix bypass via path traversal runs tasks unprompted

This page contains facts from public vulnerability sources. Check the original advisory before updating.

Copier is a library and CLI app for rendering project templates. In versions 9.5.0 through 9.15.1, the `trust` setting's prefix match (`copier/_settings.py`) compares the template URL against a trusted prefix with a raw `str.startswith` and no path normalization, while the URL is normalized when the template is actually fetched (`Path.resolve()` for local paths; libcurl dot-segment removal for `https`). A template reference that textually starts with a trusted prefix but contains `..` is therefore granted trust yet resolves to a different, attacker-controlled template, whose `tasks` / `migrations` / `jinja_extensions` then run without the `--trust` prompt — arbitrary command execution. Version 9.15.2 patches the issue.

CVSS 8.8 · High · EPSS 0.3% · Fix available

Published
Updated

Stack: python

Affected products and versions

  • copier

    Versions
    • >= 9.5.0, < 9.15.2: Affected

    No fix published

  • copier PyPI

    Versions
    • 9.10.0
    • 9.10.1
    • 9.10.2
    • 9.10.3
    • 9.11.0
    • 9.11.1
    • 9.11.2
    • 9.11.3
    • 9.12.0
    • 9.13.0
    • 9.13.1
    • 9.14.0
    • 9.14.1
    • 9.14.2
    • 9.14.3
    • 9.15.0
    • 9.15.1
    • 9.5.0
    • 9.6.0
    • 9.7.0
    • 9.7.1
    • 9.8.0
    • 9.9.0
    • 9.9.1
    Affected ranges
    • ECOSYSTEM: ≥ 9.5.0, < 9.15.2

    Update to 9.15.2

Original sources

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