{"id":"CVE-2026-77401","aliases":["GHSA-pq59-9fq7-m886","PYSEC-2026-4022"],"url":"https://o3.security/vulnerability/CVE-2026-77401","summary":"Zope AccessControl: Information disclosure through Python string `format` and `format_map` functions","details":"### Impact\nPython's string `format` functionality allows someone controlling the format string to \"read\" objects accessible (recursively) via attribute access and subscription from accessible objects. Those attribute accesses and subscriptions use Python's full blown `getattr` and `getitem`, not the policy restricted `AccessControl` variants `_getattr_` and `_getitem_`. This can lead to critical information disclosure.\n\nThe `AccessControl` package already guards against direct access to the formatting functions on string instances, but these mitigations did not cover subclasses of `str`.\n\nAffected are all users who allow untrusted users to create AccessControl controlled Python code and execute it.\n\n### Patches\nA fix was published with version 7.4.\n\n### Workarounds\nThere is no workaround.","published":"2026-09-16T14:28:01.186Z","modified":"2026-10-28T11:00:37.589386285Z","cvss":{"score":6.8,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:N/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"PyPI","name":"accesscontrol","fixedVersion":"7.4"}],"fix":{"url":"https://github.com/zopefoundation/AccessControl/commit/f980450eea416718be62847f34dfd51822938e43","label":"zopefoundation/AccessControl@f980450"},"references":[{"type":"WEB","url":"https://github.com/zopefoundation/AccessControl/releases/tag/7.4"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/77xxx/CVE-2026-77401.json"},{"type":"ADVISORY","url":"https://github.com/zopefoundation/AccessControl/security/advisories/GHSA-pq59-9fq7-m886"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-77401"},{"type":"FIX","url":"https://github.com/zopefoundation/AccessControl/commit/f980450eea416718be62847f34dfd51822938e43"},{"type":"PACKAGE","url":"https://github.com/zopefoundation/AccessControl"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-28T11:00:37.589386285Z"}}