try/except* clauses could allow bypass RestrictedPython via type confusion bug in the CPython interpreter

Vulnerability Description

RestrictedPython is a tool that helps to define a subset of the Python language which allows to provide a program input into a trusted environment. Via a type confusion bug in versions of the CPython interpreter starting in 3.11 and prior to 3.13.2 when using `try/except*`, RestrictedPython starting in version 6.0 and prior to version 8.0 could be bypassed. The issue is patched in version 8.0 of RestrictedPython by removing support for `try/except*` clauses. No known workarounds are available.

References

• https://github.com/zopefoundation/RestrictedPython/security/advisories/GHSA-gmj9-h825-chq2
• https://github.com/zopefoundation/RestrictedPython/commit/48a92c5bb617a647cffd0dadd4d5cfe626bcdb2f