CVE-2023-41050 is a medium-severity (CVSS 6.8) Information Exposure vulnerability in accesscontrol. A fix is available for accesscontrol — see the affected versions and patch details below.
Information disclosure through Python's "format" functionality in Zope AccessControl
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2023-41050.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2023-41050 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,333 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
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 | 4.4pip install --upgrade 'accesscontrol==4.4' |
| 🐍PyPI | zope | all versions | 4.8.9pip install --upgrade 'zope==4.8.9' |
| 🐍PyPI | accesscontrol | ≥ 5.0&&< 5.8 | 5.8pip install --upgrade 'accesscontrol==5.8' |
| 🐍PyPI | accesscontrol | ≥ 6.0&&< 6.2 | 6.2pip install --upgrade 'accesscontrol==6.2' |
| 🐍PyPI | zope | ≥ 5.0.0&&< 5.8.4 | 5.8.4pip install --upgrade 'zope==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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2023-41050 can be triaged on real exposure rather than presence alone.
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 Security finds CVE-2023-41050 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.