Arbitrary file write via absolute upload filename
Published Jan 27, 2026 · Updated Jan 27, 2026
Path traversal in Kludex python-multipart before 0.0.22 allows remote attackers to write files outside the configured upload directory. The File constructor preserves an attacker-supplied absolute filename and passes it through os.path.join, which discards the configured upload directory. Exploitation requires UPLOAD_DIR, UPLOAD_KEEP_FILENAME=True, and an upload larger than MAX_MEMORY_FILE_SIZE, after which the process writes to an attacker-chosen path with its filesystem privileges.
Summary
What happened
Path traversal in Kludex python-multipart before 0.0.22 allows remote attackers to write files outside the configured upload directory. The File constructor preserves an attacker-supplied absolute filename and passes it through os.path.join, which discards the configured upload directory. Exploitation requires UPLOAD_DIR, UPLOAD_KEEP_FILENAME=True, and an upload larger than MAX_MEMORY_FILE_SIZE, after which the process writes to an attacker-chosen path with its filesystem privileges.
The record
- CVE
- CVE-2026-24486
- Published
- Jan 27, 2026
- Updated
- Jan 27, 2026
- Vendor
- Kludex
- Product
- python-multipart
- Classifications
- CWE-22, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jan 27, 2026CVE publishedPublication date reported by the CVE source.
- Jan 27, 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?
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- Affected versionversion=< 0.0.22
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Your stack
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