CVE-2016-3954 is a medium-severity (CVSS 5.5) Information Exposure vulnerability in web2py. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for web2py — see the affected versions and patch details below.
web2py exposure of sensitive information
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
web2pyReal-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
web2py before 2.14.2 allows remote attackers to obtain the session_cookie_key value via a direct request to examples/simple_examples/status. NOTE: this issue can be leveraged by remote attackers to execute arbitrary code using CVE-2016-3957.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | web2py | all versions | 2.14.2pip install --upgrade 'web2py==2.14.2' |
Affected Products
web2pyweb2pyResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for web2py, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update web2py to 2.14.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2016-3954 is resolved across your whole dependency graph.
Workarounds
Assume what was exposed is already known: rotate any credential, token or key that the affected component could return, restrict the endpoint to callers that genuinely need it, and strip sensitive fields from responses and error output at the boundary rather than relying on the client not to read them.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
Frequently Asked Questions
Is CVE-2016-3954 in your dependencies?
Find it across PyPI, including transitive dependencies.