Arbitrary file writes via double URL decoding
Published Jul 29, 2026 · Updated Jul 29, 2026
Absolute path traversal in pip before 26.2 allows attackers controlling a package index to write files outside the download directory. Link.init percent-decodes the URL path, and Link.filename decodes its basename again, converting a doubly encoded separator into a path separator. Exploitation requires a user to download or install from the malicious index; the material additional risk is pip download with --only-binary.
Summary
What happened
Absolute path traversal in pip before 26.2 allows attackers controlling a package index to write files outside the download directory. Link.init percent-decodes the URL path, and Link.filename decodes its basename again, converting a doubly encoded separator into a path separator. Exploitation requires a user to download or install from the malicious index; the material additional risk is pip download with --only-binary.
The record
- CVE
- CVE-2026-13346
- Published
- Jul 29, 2026
- Updated
- Jul 29, 2026
- Vendor
- Python Packaging Authority
- Product
- pip
- Classifications
- CWE-36, T1195.002
- Attack vector
- network
- Privileges
- Unavailable
Timeline
How it unfolded
- Jul 29, 2026CVE publishedPublication date reported by the CVE source.
- Jul 29, 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 <26.2
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Public exploit references
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Technologies
Your stack
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Your stack
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