CVE-2018-16395

Severity: critical (CVSS 9.8 v3.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 10.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2018-11-16 · updated 2026-06-17

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 products

Canonical Ubuntu Linux: 14.04, 16.04, 18.04, 18.10
Debian Linux: 8.0, 9.0
Red Hat Enterprise Linux: 7.4
ruby-lang Openssl: before 2.1.2 — fixed in 2.1.2
Ruby: from 2.3.0 through 2.3.7; from 2.4.0 through 2.4.4; from 2.5.0 through 2.5.1; 2.6.0-preview1, 2.6.0-preview2

How to fix

Upgrade to a fixed version: ruby-lang Openssl 2.1.2. Check the vendor advisory for mitigations.

References

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