What’s Vulnerable › Vulnerabilities

CVE-2026-77401: Zope AccessControl: Information disclosure through Python string `format` and `format_map` functions

• Severity: medium (CVSS 6.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-16 · updated 2026-09-30
• Weakness: CWE-693

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.

Affected products

• zopefoundation AccessControl: before 7.4

References

• 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

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