JRuby-OpenSSL has hostname verification disabled by default
Summary
When verifying SSL certificates, jruby-openssl is not verifying that the hostname presented in the certificate matches the one we are trying to connect to, meaning a MITM could just present any valid cert for a completely different domain they own, and JRuby wouldn't complain.
Details
n/a
PoC
An example domain bad.substitutealert.com was created to present the a certificate for the domain s8a.me. The following script run in IRB in CRuby 3.4.3 will fail with certificate verify failed (hostname mismatch), but will work just fine in JRuby 10.0.0.0 and JRuby 9.4.2.0, both of which use jruby-openssl version 0.15.3
require "net/http"
require "openssl"
uri = URI("https://bad.substitutealert.com/")
https = Net::HTTP.new(uri.host, uri.port)
https.use_ssl = true
https.verify_mode = OpenSSL::SSL::VERIFY_PEER
body = https.start { https.get(uri.request_uri).body }
puts bodyImpact
Anybody using JRuby to make requests of external APIs, or scraping the web, that depends on https to connect securely
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Java / Kotlin (Maven) | org.jruby:jruby | >= 10.0.0.0, < 10.0.0.1, >= 9.3.4.0, < 9.4.12.1 | 10.0.0.1, 9.4.12.1 |
| Java / Kotlin (Maven) | rubygems:jruby-openssl | >= 0.12.1, < 0.15.4 | 0.15.4 |
References
- https://github.com/jruby/jruby-openssl/security/advisories/GHSA-72qj-48g4-5xgx
- https://nvd.nist.gov/vuln/detail/CVE-2025-46551
- https://github.com/jruby/jruby-openssl/commit/31a56d690ce9b8af47af09aaaf809081949ed285
- https://github.com/jruby/jruby-openssl/commit/b1fc5d645c0d90891b8865925ac1c15e3f15a055
- https://github.com/jruby/jruby-openssl
- https://github.com/rubysec/ruby-advisory-db/blob/master/gems/jruby-openssl/CVE-2025-46551.yml
- CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P- Weakness (CWE)
CWE-295, CWE-297- Platform
- Java / Kotlin (Maven)
- Package
org.jruby:jruby, rubygems:jruby-openssl- Disclosed
- 07.05.2025
- Updated
- 11.10.2026 13:20
Sources and licenses
OSV / GitHub Advisory Database - GHSA-72qj-48g4-5xgx - CC BY 4.0
Vulnerability history: org.jruby:jruby
All published vulnerabilities of this package (Java / Kotlin (Maven)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 2
- First → latest
- 05.2022 05.2025
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Medium 2
Disclosures per year
- 2022: 1
- 2023: 0
- 2024: 0
- 2025: 1
- 2026: 0
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JRuby-OpenSSL has hostname verification disabled by default this entry
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