CVE-2018-16395 is a critical-severity (CVSS 9.8) vulnerability in openssl. EPSS puts its 30-day exploitation probability at 10.7% (96th percentile). A fix is available for openssl — see the affected versions and patch details below.
Ruby Openssl Allows Incorrect Value Comparison
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
openssl💎opensslReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.
Description
An issue was discovered in the OpenSSL library in Ruby before 2.3.8, 2.4.x before 2.4.5, 2.5.x before 2.5.2, and 2.6.x before 2.6.0-preview3. When two OpenSSL::X509::Name objects are compared using ==, depending on the ordering, non-equal objects may return true. When the first argument is one character longer than the second, or the second argument contains a character that is one less than a character in the same position of the first argument, the result of == will be true. This could be leveraged to create an illegitimate certificate that may be accepted as legitimate and then used in signing or encryption operations.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | openssl | all versions | 2.0.9bundle update openssl --conservative |
| 💎RubyGems | openssl | ≥ 2.1.0&&< 2.1.2 | 2.1.2bundle update openssl --conservative |
Affected Products
ubuntu linuxcanonicaldebian linuxdebianenterprise linuxredhatopensslruby-langrubyruby-langDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for openssl, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update openssl to 2.0.9 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2018-16395 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.
Subscription Asset Manager is now in a reduced support phase receiving only Critical impact security fixes. This issue has been rated as having a security impact of Important, and is not currently planned to be addressed in future updates. Red Hat Virtualization includes a vulnerable version of ruby, however the…
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 7 | ruby-0:2.0.0.648-34.el7_6 | RHSA-2018:3738 |
| Red Hat Enterprise Linux 7.4 Extended Update Support | ruby-0:2.0.0.648-34.el7_4 | RHSA-2019:1948 |
| Red Hat Enterprise Linux 7.5 Extended Update Support | ruby-0:2.0.0.648-34.el7_5 | RHSA-2019:2565 |
| Red Hat Software Collections for Red Hat Enterprise Linux 6 | rh-ruby23-ruby-0:2.3.8-69.el6 | RHSA-2018:3729 |
| Red Hat Software Collections for Red Hat Enterprise Linux 6 | rh-ruby24-ruby-0:2.4.5-91.el6 | RHSA-2018:3730 |
| Red Hat Software Collections for Red Hat Enterprise Linux 7 | rh-ruby25-ruby-0:2.5.3-6.el7 | RHSA-2018:3731 |
Frequently Asked Questions
Is CVE-2018-16395 in your dependencies?
Find it across RubyGems, including transitive dependencies.