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💎 RubyGems
Not in CISA KEV
HIGH severity

GHSA-fp4w-jxhp-m23p bundler

HIGHFix: rubygems/rubygems#4609

GHSA-fp4w-jxhp-m23p is a high-severity (CVSS 8.8) vulnerability in bundler. 2 public exploit references exist, so weaponization risk is real. A fix is available for bundler — see the affected versions and patch details below.

Dependency Confusion in Bundler

Also known asCVE-2020-36327
Published
May 24, 2021
Updated
Dec 5, 2024
Affected
2 pkgs
Patched
2 / 2
Exploits
2 known
Exploitation data as of Sep 19, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
6.3%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs93th percentile — riskier than 93% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

How urgent is this, really

GHSA-fp4w-jxhp-m23p plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.

Where this sits among everything scored

Of 377,166 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.

Real-World Exposure

2 pkgs affected
💎bundler💎bundler

Real-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

Bundler 1.16.0 through 2.2.9 and 2.2.11 through 2.2.17 sometimes chooses a dependency source based on the highest gem version number, which means that a rogue gem found at a public source may be chosen, even if the intended choice was a private gem that is a dependency of another private gem that is explicitly depended on by the application.

Affected Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
💎RubyGemsbundler1.16.0&&< 2.2.102.2.10bundle update bundler --conservative
💎RubyGemsbundler2.2.11&&< 2.2.182.2.18bundle update bundler --conservative
Exploits & PoCs
2

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for bundler, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update bundler to 2.2.10 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-fp4w-jxhp-m23p is resolved across your whole dependency graph.

  3. 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.

  4. How O3 protects you

    O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-fp4w-jxhp-m23p can be triaged on real exposure rather than presence alone.

Tailored to GHSA-fp4w-jxhp-m23p. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

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.

Red HatImportant

Red Hat Satellite does not ship RubyGem bundler, however, the product consumes it from the Red Hat Software Collections (RHSCL) repository.

ProductFixed inAdvisory
Red Hat Enterprise Linux 8ruby:2.7-8040020210728141159.522a0ee4RHSA-2021:3020
Red Hat Enterprise Linux 8ruby:2.6-8050020211215144356.c5368500RHSA-2022:0543
Red Hat Enterprise Linux 8ruby:2.5-8050020220112131355.c5368500RHSA-2022:0545
Red Hat Enterprise Linux 8.1 Update Services for SAP Solutionsruby:2.5-8010020220201125517.c27ad7f8RHSA-2022:0548
Red Hat Enterprise Linux 8.1 Update Services for SAP Solutionsruby:2.6-8010020220201152941.c27ad7f8RHSA-2022:0581
Red Hat Enterprise Linux 8.2 Extended Update Supportruby:2.5-8020020220201125131.4cda2c84RHSA-2022:0547
Red Hat Enterprise Linux 8.2 Extended Update Supportruby:2.6-8020020220201131207.4cda2c84RHSA-2022:0582
Red Hat Enterprise Linux 8.4 Extended Update Supportruby:2.6-8040020220131135901.522a0ee4RHSA-2022:0544

Frequently Asked Questions

Bundler 1.16.0 through 2.2.9 and 2.2.11 through 2.2.17 sometimes chooses a dependency source based on the highest gem version number, which means that a rogue gem found at a public source may be chosen, even if the intended choice was a private gem that is a dependency of another private gem that is explicitly depended on by the application.
O3 Security · Impact-Aware SCA

Is GHSA-fp4w-jxhp-m23p in your dependencies?

O3 Security finds GHSA-fp4w-jxhp-m23p across RubyGems dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

GHSA-fp4w-jxhp-m23p: bundler (High 8.8) | O3 Security