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CVE-2017-17790

CRITICAL · 9.8 CVSS v3.0 Published 2017-12-20
Fix available
A fix is available. Upgrade to after 2.4.2 or later.
See remediation →
100/100
Remediation priority · Urgent
Public exploit Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-74

Untrusted input crosses into a downstream interpreter — SQL, a shell, an HTML page, an LDAP query — without being kept separate from the commands around it, so the attacker's data is read as instructions. This is the parent class behind SQL injection, cross-site scripting, and command injection alike. The durable fix is the same everywhere: keep data and code apart at every boundary, using parameterisation or context-aware encoding rather than building interpreted strings by concatenation.

General guidance for the injection class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
RubyApplication
Affected:>= 2.2, <= 2.2.8>= 2.3, <= 2.3.5>= 2.4, <= 2.4.2= 2.5.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to a release after 2.4.2
Vendor patch github.com →
Recommended fix High confidence

Ruby 2.2.9, 2.3.6, 2.4.4, or 2.5.1 (latest in each supported branch)

  1. Identify the currently installed Ruby version using `ruby --version`
  2. If running Ruby 2.2.x, upgrade to Ruby 2.2.9 or later
  3. If running Ruby 2.3.x, upgrade to Ruby 2.3.6 or later
  4. If running Ruby 2.4.x, upgrade to Ruby 2.4.4 or later
  5. If running Ruby 2.5.0, upgrade to Ruby 2.5.1 or later
  6. Use a version manager like rbenv, rvm, or asdf to install the new version: `rbenv install 2.5.1` or `rvm install ruby-2.5.1`
  7. Verify the new version is active: `ruby --version`
  8. Ensure any applications using Resolv::Hosts with untrusted input are reviewed to prevent command injection
Caveat Minor version upgrades within a branch are generally safe; however, test applications that use Resolv::Hosts functionality to ensure compatibility

Generated from the published advisory — verify against the referenced sources before acting.

We can identify the exact fixed release, upgrade, and verify it in staging — typical engagement from $2,300. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2017-17790 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
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  • Version or environment caveats, and links to real fixes
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