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MEDIUM severity

CVE-2021-3779 — ruby-mysql

MEDIUM

CVE-2021-3779 is a medium-severity (CVSS 6.5) CWE-610 vulnerability in ruby-mysql. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for ruby-mysql — see the affected versions and patch details below.

Externally Controlled Reference to a Resource in Another Sphere in ruby-mysql

Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
1 known
Exploitation data as of Nov 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.2%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs68th percentile — riskier than 68% of all scored CVEsHighest risk
0.00%0.56%1.13%1.69%0.4%1.2%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
💎ruby-mysql

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

A malicious actor can read arbitrary files from a client that uses ruby-mysql to communicate to a rogue MySQL server and issue database queries. In these cases, the server has the option to create a database reply using the LOAD DATA LOCAL statement, which instructs the client to provide additional data from a local file readable by the client (and not a "local" file on the server).

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
💎RubyGemsruby-mysqlall versions2.10.0bundle update ruby-mysql --conservative

Affected Products

1 product · 1 configurations
Application
ruby-mysqlruby-mysql_project
< 2.10.0
range
Exploits & PoCs
1

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

A malicious MySQL server can request local file content from a client us…

rapid7.comNVDJul 2022

Detection & mitigation playbook

Open-source dependency

  1. Detect

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

  2. Fix

    Update ruby-mysql to 2.10.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-3779 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.

Frequently Asked Questions

A malicious actor can read arbitrary files from a client that uses ruby-mysql to communicate to a rogue MySQL server and issue database queries. In these cases, the server has the option to create a database reply using the LOAD DATA LOCAL statement, which instructs the client to provide additional data from a local file readable by the client (and not a "local" file on the server).
O3 Security · Impact-Aware SCA

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CVE-2021-3779: ruby-mysql — Fixed in 2.10.0