CVE-2026-77401: CWE-693: Protection Mechanism Failure in zopefoundation AccessControl
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.
AI Analysis
Technical Summary
CVE-2026-77401 describes a protection mechanism failure in the zopefoundation AccessControl security framework. Before version 7.4, the implementation of Python string formatting in ImplPython.py and cAccessControl.c does not enforce policy restrictions on getattr and getitem operations when these are invoked through str.format or str.format_map on a str subclass. This allows controlled format strings to recursively access and disclose objects accessible from the values used in formatting, bypassing intended security policies. The issue is resolved in version 7.4.
Potential Impact
The vulnerability allows disclosure of sensitive objects reachable via Python string formatting operations in AccessControl-controlled code. This can lead to confidentiality breaches by exposing internal objects that should be protected by AccessControl policies. The CVSS 3.1 score is 6.8 (medium severity), reflecting network attack vector, low attack complexity, high privileges required, no user interaction, and a confidentiality impact without integrity or availability impact.
Mitigation Recommendations
Upgrade to AccessControl version 7.4 or later, where this issue is fixed. No other mitigation or workaround is indicated. Since this is a code-level security framework vulnerability, applying the official fix is the recommended remediation.
CVE-2026-77401: CWE-693: Protection Mechanism Failure in zopefoundation AccessControl
Description
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.
CVSS v3.1
Score 6.8medium
Affected software
zopefoundation
AccessControl
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-77401 describes a protection mechanism failure in the zopefoundation AccessControl security framework. Before version 7.4, the implementation of Python string formatting in ImplPython.py and cAccessControl.c does not enforce policy restrictions on getattr and getitem operations when these are invoked through str.format or str.format_map on a str subclass. This allows controlled format strings to recursively access and disclose objects accessible from the values used in formatting, bypassing intended security policies. The issue is resolved in version 7.4.
Potential Impact
The vulnerability allows disclosure of sensitive objects reachable via Python string formatting operations in AccessControl-controlled code. This can lead to confidentiality breaches by exposing internal objects that should be protected by AccessControl policies. The CVSS 3.1 score is 6.8 (medium severity), reflecting network attack vector, low attack complexity, high privileges required, no user interaction, and a confidentiality impact without integrity or availability impact.
Mitigation Recommendations
Upgrade to AccessControl version 7.4 or later, where this issue is fixed. No other mitigation or workaround is indicated. Since this is a code-level security framework vulnerability, applying the official fix is the recommended remediation.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-08-20T19:55:27.023Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6aaaac0055bf5e2cf5bf8d57
Added to database: 09/16/2026, 14:47:28 UTC
Last enriched: 09/16/2026, 15:02:06 UTC
Last updated: 09/17/2026, 02:05:20 UTC
Views: 10
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