Local file disclosure via unchecked external data paths
Published Apr 2, 2026 · Updated Apr 2, 2026
Path traversal in Copier before 9.14.1 allows attackers to read local YAML-parseable files through an untrusted project template. The _external_data flow renders a template-controlled path and passes it to load_answersfile_data(), which opens it without checking destination containment. Exploitation requires a user to run the malicious template; disclosed data is limited to readable files accepted by yaml.safe_load and exposed in output.
Summary
What happened
Path traversal in Copier before 9.14.1 allows attackers to read local YAML-parseable files through an untrusted project template. The _external_data flow renders a template-controlled path and passes it to load_answersfile_data(), which opens it without checking destination containment. Exploitation requires a user to run the malicious template; disclosed data is limited to readable files accepted by yaml.safe_load and exposed in output.
The record
- CVE
- CVE-2026-34730
- Published
- Apr 2, 2026
- Updated
- Apr 2, 2026
- Vendor
- copier-org
- Product
- Copier
- Classifications
- CWE-22, T1005
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 2, 2026CVE publishedPublication date reported by the CVE source.
- Apr 2, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 9.14.1
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Upstream _external_data relative and absolute path PoCsproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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