The import hook in CPython that handles legacy *.pyc files (SourcelessFileLoader) is incorrectly handled in FileLoader (a base class) and so does not use io.open_code() to read the .pyc files. sys.audit handlers for this audit event therefore do not fire.
Attack Parameters
Attack Vector
Local
Requires local access
Attack Complexity
Low
Easy to exploit
Attack Requirements
Present
Additional conditions required
Privileges Required
Low
Basic privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
None
No data leak
Integrity
High
Complete data modification
Availability
None
No disruption
CVSS Vector v4.0
References 6
https://github.com/python/cpython/commit/482d6f8bdba9da3725d272e8bb4a2d25fb6a60…
cna@python.org
https://github.com/python/cpython/commit/a51b1b512de1d56b3714b65628a2eae2b07e53…
cna@python.org
https://github.com/python/cpython/commit/e58e9802b9bec5cdbf48fc9bf1da5f4fda482e…
cna@python.org
https://github.com/python/cpython/issues/145506
cna@python.org
https://github.com/python/cpython/pull/145507
cna@python.org
http://www.openwall.com/lists/oss-security/2026/03/05/6
af854a3a-2127-422b-91ae-364da2661108