CVE-2016-10149 is a high-severity (CVSS 7.5) XML External Entity (XXE) vulnerability in pysaml2. A fix is available for pysaml2 — see the affected versions and patch details below.
Pysaml2 does not sanitize XML responses
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
pysaml2Real-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
XML External Entity (XXE) vulnerability in PySAML2 4.4.0 and earlier allows remote attackers to read arbitrary files via a crafted SAML XML request or response.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | pysaml2 | all versions | 4.5.0pip install --upgrade 'pysaml2==4.5.0' |
Affected Products
debian linuxdebianpysaml2pysaml2_projectDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pysaml2, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update pysaml2 to 4.5.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2016-10149 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.
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.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat OpenStack Platform 10.0 (Newton) | python-defusedxml-0:0.5.0-1.el7ost | RHSA-2017:0938 |
| Red Hat OpenStack Platform 8.0 (Liberty) | python-defusedxml-0:0.5.0-1.el7ost | RHSA-2017:0936 |
| Red Hat OpenStack Platform 9.0 (Mitaka) | python-defusedxml-0:0.5.0-1.el7ost | RHSA-2017:0937 |
Frequently Asked Questions
Is CVE-2016-10149 in your dependencies?
Find it across PyPI, including transitive dependencies.