How severe is CVE-2009-4492?

No CVSS score has been assigned to CVE-2009-4492 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2009-4492?

CVE-2009-4492 affects the following packages: webrick (RubyGems). Ecosystems affected: RubyGems.

How do I fix CVE-2009-4492?

Update webrick to 1.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2009-4492 is resolved across your whole dependency graph.

How do I detect CVE-2009-4492 in my RubyGems dependencies?

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

How do I mitigate CVE-2009-4492 if there is no patch (or I can't update yet)?

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.

Is CVE-2009-4492 actively exploited in the wild?

Yes. There are 4 known exploit references for CVE-2009-4492, including 1 documented proof-of-concept exploit on Exploit-DB and 3 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2009-4492?

CVE-2009-4492 has an EPSS (Exploit Prediction Scoring System) score of 16.2%, placing it in the 97th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score warrants monitoring and prompt remediation.

When was CVE-2009-4492 published, and has it been updated?

CVE-2009-4492 was published on October 24, 2017 and was last updated on May 22, 2025. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

💎 RubyGems

Not in CISA KEV

CVE-2009-4492 — webrick

CVE-2009-4492 is a security vulnerability in webrick. 4 public exploit or proof-of-concept references are indexed, so weaponization risk is real. A fix is available for webrick — see the affected versions and patch details below.

WEBrick Improper Input Validation vulnerability

Published

Oct 24, 2017

Updated

May 22, 2025

Affected

1 pkg

Patched

1 / 1

Exploits

4 known

Exploitation data as of Nov 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

16.2%probability of exploitation in next 30 days

Moderate Risk0.00%

Lower risk than most CVEs97th percentile — riskier than 97% of all scored CVEsHighest risk

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

Real-World Exposure

1 pkg affected

💎webrick

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

WEBrick 1.3.1 in Ruby 1.8.6 through patchlevel 383, 1.8.7 through patchlevel 248, 1.8.8dev, 1.9.1 through patchlevel 376, and 1.9.2dev writes data to a log file without sanitizing non-printable characters, which might allow remote attackers to modify a window's title, or possibly execute arbitrary commands or overwrite files, via an HTTP request containing an escape sequence for a terminal emulator.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
💎RubyGems	`webrick`	all versions	1.4.0`bundle update webrick --conservative`

Affected Products

1 product · 1 configurations

Application

webrickruby-lang

1 version

1.3.1

Exploits & PoCs

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

EDB-33489remotemultiple✓ Verified

Ruby 1.9.1 - WEBrick 'Terminal Escape Sequence in Logs' Command Injection

by evilaliv3 · Jan 11, 2010

Exploit-DB Source

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for webrick, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update webrick to 1.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2009-4492 is resolved across your whole dependency graph.
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.

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 HatLow

Product	Fixed in	Advisory
Red Hat Enterprise Linux 4	`ruby-0:1.8.1-16.el4`	RHSA-2011:0908
Red Hat Enterprise Linux 5	`ruby-0:1.8.5-19.el5_6.1`	RHSA-2011:0909

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2009-4492 in your dependencies?

Find it across RubyGems, including transitive dependencies.

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