What is CVE-2017-17790?

CVE-2017-17790 is a critical-severity vulnerability in Ruby-Lang Ruby, classified under Improper Neutralization of Special Elements in Output Used by a Downstream Component (Injection). CVSS score: 9.8/10. Published 2017-12-20.

How severe is CVE-2017-17790?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Is CVE-2017-17790 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Vulnerability in Ruby-Lang Ruby

CVE-2017-17790

The lazy_initialize function in lib/resolv.rb in Ruby through 2.4.3 uses Kernel#open, which might allow Command Injection attacks, as demonstrated by a Resolv::Hosts::new argument beginning with a '|' character, a different vulnerability than CVE-2017-17405. NOTE: situations with untrusted input may be highly unlikely.

Published 2017-12-20 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.059 (93.2th percentile), scored 2026-10-18.

Low probability of exploitation in the next 30 days, but still tracked. 93rd percentile — 93.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.059 · newest: 0.059 · change: 0.000

Affected products

Ruby-Lang Ruby — versions 2.5.0

Weakness classification (CWE)

CWE-74 — Improper Neutralization of Special Elements in Output Used by a Downstream Component (Injection)

Public proof-of-concept exploits

ARPSyndicate/cvemon

References

access.redhat.com/errata/RHSA-2018:0585 (vendor-advisory)
lists.debian.org/debian-lts-announce/2017/12/msg00024.html (mailing-list)
access.redhat.com/errata/RHSA-2018:0378 (vendor-advisory)
github.com/ruby/ruby/pull/1777 (Exploit, Third Party Advisory, Issue Tracking)
access.redhat.com/errata/RHSA-2018:0584 (vendor-advisory)
lists.debian.org/debian-lts-announce/2018/07/msg00012.html (mailing-list)
access.redhat.com/errata/RHSA-2018:0583 (vendor-advisory)
lists.debian.org/debian-lts-announce/2017/12/msg00025.html (mailing-list)
www.debian.org/security/2018/dsa-4259 (vendor-advisory)

Frequently asked questions

What is CVE-2017-17790?: CVE-2017-17790 is a critical-severity vulnerability in Ruby-Lang Ruby, classified under Improper Neutralization of Special Elements in Output Used by a Downstream Component (Injection). CVSS score: 9.8/10. Published 2017-12-20.
How severe is CVE-2017-17790?: Critical severity. CVSS v3 base score is 9.8 out of 10.
Is CVE-2017-17790 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.