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.
https://github.com/python/cpython/pull/145507
https://github.com/python/cpython/issues/145506
https://github.com/python/cpython/commit/e58e9802b9bec5cdbf48fc9bf1da5f4fda482e86
https://github.com/python/cpython/commit/a51b1b512de1d56b3714b65628a2eae2b07e535e
https://github.com/python/cpython/commit/482d6f8bdba9da3725d272e8bb4a2d25fb6a603e
Published: 2026-03-04
Updated: 2026-03-05
Base Score: 6.4
Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:N
Severity: Medium
Base Score: 7.5
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Severity: High
Base Score: 5.7
Vector: CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
Severity: Medium
EPSS: 0.00014