CVE-2026-53951

Severity CVSS v4.0:

HIGH

Type:

CWE-22 Path Traversal

Publication date:

08/07/2026

Last modified:

10/07/2026

Description

Copier is a library and CLI app for rendering project templates. In versions 9.5.0 through 9.15.1, the `trust` setting&#39;s prefix match<br /> (`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.

Impact

Vector 4.0

CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H CVSS v4.0 Severity and Metrics:

Base Score: 8.80 HIGH
Vector: CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

Attack Vector (AV): Local
Attack Complexity (AC): Low
Attack Requirements (AT): Present
Privileges Required (PR): None
User Interaction (UI): Passsive
Confidentiality (VC): High
Integrity (VI): High
Availability (VA): High
Confidentiality (SC): High
Integrity (SI): High
Availability (SA): High

Base Score 4.0

8.80

Severity 4.0

HIGH

CVE-2026-53951

Description

Impact

References to Advisories, Solutions, and Tools