What’s Vulnerable › Vulnerabilities

CVE-2026-12345: Race condition in tempfile.TemporaryDirectory cleanup allows deleting files outside the temporary directory

• Severity: medium (CVSS 5.9 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-29 · updated 2026-10-26
• Weakness: CWE-59

Description

The cleanup of tempfile.TemporaryDirectory is vulnerable to a race condition. An attacker who can modify the tree during cleanup can replace a directory with a symbolic link, causing files outside of the temporary directory to be deleted or have their permissions and file flags reset, with the privileges of the process performing the cleanup. Note that platforms where shutil.rmtree.avoids_symlink_attacks is false, remain affected, and file flags may still be reset outside of the tree on all platforms.

Affected products

• Python: before 3.12.15; from 3.14.0 before 3.14.9; from 3.15.0a1 before 3.15.0rc3 — fixed in 3.12.15, 3.14.9, 3.15.0rc3

How to fix

Upgrade to a fixed version: Python 3.12.15, 3.14.9, 3.15.0rc3. Check the vendor advisory for mitigations.

References

• https://github.com/python/cpython/commit/0478b52788117db4b831b3efd648f56b777628aa
• https://github.com/python/cpython/commit/06ef3d43fdaf4da97af12fa694b4886092c4b970
• https://github.com/python/cpython/commit/458e7134a5af7f86aee9d21b51cf499b41aa4420
• https://github.com/python/cpython/commit/58ed0259cae509a19138795df302fe60b544dc74
• https://github.com/python/cpython/commit/5c20517a4fc56683efe63a7751020db9573f538d
• https://github.com/python/cpython/commit/c39b52d00b42200aaadff679e2fe3f1006d57c58
• https://github.com/python/cpython/commit/e1f3590f155c6d66007e958c98c9d69316551993
• https://github.com/python/cpython/issues/157579
• https://github.com/python/cpython/pull/157580
• http://www.openwall.com/lists/oss-security/2026/09/29/40

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