PT-2026-56480 · Copier Org · Copier

Published 2026-07-08 · Updated 2026-07-08 · CVE-2026-53951

NVD

CVSS v4.0

8.8

High

Base vector

AV:L/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

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.

Fix

Code Injection

Path traversal

Weakness Enumeration

CWE-94

CWE-22

Related Identifiers

CVE-2026-53951

Affected Products

Copier

References · 3

• https://nvd.nist.gov/vuln/detail/CVE-2026-53951 · Security Note
• https://github.com/copier-org/copier/security/advisories/GHSA-9gmc-jqmh-3rvm · Note
• https://github.com/copier-org/copier/releases/tag/v9.15.2 · Note