Cache poisoning via symlink directory races
Published Jan 10, 2026 · Updated Jan 10, 2026
TOCTOU flaws in virtualenv before 20.36.1 allow local users to redirect app-data and lock operations through symlink races. The make_app_data function and lock constructors check whether directories exist before creating them, leaving paths replaceable between operations. Exploitation requires write access to a shared parent directory and winning the race; it can poison caches, expose cached data, bypass locks, or interrupt virtualenv operations.
Summary
What happened
TOCTOU flaws in virtualenv before 20.36.1 allow local users to redirect app-data and lock operations through symlink races. The make_app_data function and lock constructors check whether directories exist before creating them, leaving paths replaceable between operations. Exploitation requires write access to a shared parent directory and winning the race; it can poison caches, expose cached data, bypass locks, or interrupt virtualenv operations.
The record
- CVE
- CVE-2026-22702
- Published
- Jan 10, 2026
- Updated
- Jan 10, 2026
- Vendor
- Python Packaging Authority
- Product
- virtualenv
- Classifications
- CWE-362, CWE-59
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Jan 10, 2026CVE publishedPublication date reported by the CVE source.
- Jan 10, 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=< 20.36.1
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
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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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