CVE-2023-41050
MEDIUMCVE-2023-41050 is a medium-severity (CVSS 6.8) Information Exposure vulnerability in accesscontrol. O3 Security confirms whether CVE-2023-41050 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Information disclosure through Python's "format" functionality in Zope AccessControl
Blast Radius
accesscontrol🐍zope🐍accesscontrol🐍accesscontrol🐍zopeReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
AccessControl provides a general security framework for use in Zope. Python's "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. AccessControl already provides a safe variant for str.format and denies access to string.Formatter. However, str.format_map is still unsafe. Affected are all users who allow untrusted users to create AccessControl controlled Python code and execute it. A fix has been introduced in versions 4.4, 5.8 and 6.2. Users are advised to upgrade. There are no known workarounds for this vulnerability.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | accesscontrol | all versions | 4.4 |
| 🐍PyPI | zope | all versions | 4.8.9 |
| 🐍PyPI | accesscontrol | ≥ 5.0&&< 5.8 | 5.8 |
| 🐍PyPI | accesscontrol | ≥ 6.0&&< 6.2 | 6.2 |
| 🐍PyPI | zope | ≥ 5.0.0&&< 5.8.4 | 5.8.4 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for accesscontrol. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update accesscontrol to 4.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-41050 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2023-41050 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2023-41050. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2023-41050 in your dependencies?
O3 detects CVE-2023-41050 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.