CVE-2026-53951
Copier is a library and CLI app for rendering project templates.
Overview
CVE-2026-53951 is a known-severity vulnerability. It was published on July 8, 2026.
Technical description
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.
Remediation
Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
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Frequently asked questions
What is CVE-2026-53951?
CVE-2026-53951 is a known-severity vulnerability. It was published on July 8, 2026.
How severe is CVE-2026-53951?
CVSS score information is not yet available for this vulnerability. Check back as the CVE record is updated by NVD analysts.
How do I fix or remediate CVE-2026-53951?
Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-53951?
CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-53951 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.