CVE-2018-1000807 is a high-severity (CVSS 8.1) Use After Free vulnerability in pyopenssl. A fix is available for pyopenssl — see the affected versions and patch details below.
PyOpenSSL Use-After-Free vulnerability
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
pyopensslReal-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
Python Cryptographic Authority pyopenssl version prior to version 17.5.0 contains a CWE-416: Use After Free vulnerability in X509 object handling that can result in Use after free can lead to possible denial of service or remote code execution.. This attack appear to be exploitable via Depends on the calling application and if it retains a reference to the memory.. This vulnerability appears to have been fixed in 17.5.0.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | pyopenssl | all versions | 17.5.0pip install --upgrade 'pyopenssl==17.5.0' |
Affected Products
ubuntu linuxcanonicalpyopensslpyopensslenterprise linux desktopredhatenterprise linux serverredhatenterprise linux workstationredhatopenstackredhatDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pyopenssl, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update pyopenssl to 17.5.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2018-1000807 is resolved across your whole dependency graph.
Workarounds
Constrain what reaches the vulnerable code: limit the size and shape of untrusted input, isolate the affected component in a sandboxed or least-privileged process, and enable the platform's memory-safety mitigations (ASLR, stack protector, hardened allocator) so an out-of-bounds access is more likely to fail closed than to be exploitable.
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.
This vulnerability is only present when a specific and uncommon usage pattern of pyOpenSSL occurs. Red Hat Product Security has audited our packages that use pyOpenSSL, and determined that software we distribute in Red Hat Enterprise Linux and Red Hat Virtualization does not use pyOpenSSL in such a way as to be…
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat OpenStack Platform 13.0 (Queens) | pyOpenSSL-0:17.5.0-1.el7ost | RHSA-2019:0085 |
Frequently Asked Questions
Is CVE-2018-1000807 in your dependencies?
Find it across PyPI, including transitive dependencies.