CVE-2026-77401

Zope AccessControl provides a general security framework for use in Zope. Prior to 7.4, applications that allow untrusted users to create and execute AccessControl-controlled Python code do not safely guard str.format and str.format_map when those methods are reached through a str subclass. In both ImplPython.py and cAccessControl.c, Python formatting can recursively access attributes and subscriptions using unrestricted getattr and getitem behavior instead of the policy-restricted getattr and getitem operations. A controlled format string can therefore disclose objects reachable from values available to the formatting operation. This issue is fixed in version 7.4.

• https://github.com/zopefoundation/AccessControl/commit/f980450eea416718be62847f34dfd51822938e43
• https://github.com/zopefoundation/AccessControl/releases/tag/7.4
• https://github.com/zopefoundation/AccessControl/security/advisories/GHSA-pq59-9fq7-m886