Out-of-directory file access via hardlink-symlink fallback
Published Jun 23, 2026 · Updated Jun 23, 2026
Path traversal in CPython before 3.15.0 allows attackers to read or write files outside an extraction directory via a crafted tar archive. The tarfile hardlink fallback validates a referenced symlink at its deeper archived name, then recreates it at the hardlink's shallower path without rechecking the relative target there. Exploitation requires an application to extract an attacker-controlled archive with the data or tar filter, after which the escaped symlink permits out-of-directory file access.
Summary
What happened
Path traversal in CPython before 3.15.0 allows attackers to read or write files outside an extraction directory via a crafted tar archive. The tarfile hardlink fallback validates a referenced symlink at its deeper archived name, then recreates it at the hardlink's shallower path without rechecking the relative target there. Exploitation requires an application to extract an attacker-controlled archive with the data or tar filter, after which the escaped symlink permits out-of-directory file access.
The record
- CVE
- CVE-2026-11940
- Published
- Jun 23, 2026
- Updated
- Jun 23, 2026
- Vendor
- Python Software Foundation
- Product
- CPython
- Classifications
- CWE-22, T1565.001
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 23, 2026CVE publishedPublication date reported by the CVE source.
- Jun 23, 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=0 <3.15.0
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
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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