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Vulnerability record · CVE-2009-4492 · published 13 January 2010

CVE-2009-4492: Ruby-lang webrick vulnerability

Ruby Lang · Webrick

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.

7.5 CVSS 2.0 High EPSS 16% · top 3.2%
7.5CVSS 2.0 base score
16%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
18References, 6 tagged exploit
16 Jun 2026Last modified by NVD

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.

AV:N/AC:L/Au:N/C:P/I:P/A:P

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
http://secunia.com/advisories/37949 Not ApplicableVendor Advisory
http://securitytracker.com/id?1023429 Broken LinkExploitThird Party AdvisoryVDB Entry
http://www.redhat.com/support/errata/RHSA-2011-0908.html Third Party Advisory
http://www.redhat.com/support/errata/RHSA-2011-0909.html Third Party Advisory
http://www.ruby-lang.org/en/news/2010/01/10/webrick-escape-sequence-injection PatchVendor Advisory
http://www.securityfocus.com/archive/1/508830/100/0/threaded Broken LinkThird Party AdvisoryVDB Entry
http://www.securityfocus.com/bid/37710 Broken LinkExploitThird Party AdvisoryVDB Entry
http://www.ush.it/team/ush/hack_httpd_escape/adv.txt Broken LinkExploit
http://www.vupen.com/english/advisories/2010/0089 Permissions Required
http://secunia.com/advisories/37949 Not ApplicableVendor Advisory
http://securitytracker.com/id?1023429 Broken LinkExploitThird Party AdvisoryVDB Entry
http://www.redhat.com/support/errata/RHSA-2011-0908.html Third Party Advisory
http://www.redhat.com/support/errata/RHSA-2011-0909.html Third Party Advisory
http://www.ruby-lang.org/en/news/2010/01/10/webrick-escape-sequence-injection PatchVendor Advisory
http://www.securityfocus.com/archive/1/508830/100/0/threaded Broken LinkThird Party AdvisoryVDB Entry
http://www.securityfocus.com/bid/37710 Broken LinkExploitThird Party AdvisoryVDB Entry
http://www.ush.it/team/ush/hack_httpd_escape/adv.txt Broken LinkExploit
http://www.vupen.com/english/advisories/2010/0089 Permissions Required

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

7.5CVE-2020-25613Ruby-lang ruby http request smuggling vulnerabilityAn issue was discovered in Ruby through 2.5.8, 2.6.x through 2.6.6, and 2.7.x through 2.7.1. WEBrick, a simple HTTP server bundled with Ruby, had not…EPSS 3.8%5.9CVE-2025-6442Ruby-lang webrick http request smuggling vulnerabilityRuby WEBrick read_header HTTP Request Smuggling Vulnerability. This vulnerability allows remote attackers to smuggle arbitrary HTTP requests on affec…EPSS 0.50%5.5CVE-2019-11879Ruby-lang webrick path traversal vulnerabilityThe WEBrick gem 1.4.2 for Ruby allows directory traversal if the attacker once had local access to create a symlink to a location outside of the web …EPSS 0.55%5.0CVE-2008-1145Ruby-lang webrick path traversal vulnerabilityDirectory traversal vulnerability in WEBrick in Ruby 1.8 before 1.8.5-p115 and 1.8.6-p114, and 1.9 through 1.9.0-1, when running on systems that supp…EPSS 28%

Source: NIST National Vulnerability Database (record CVE-2009-4492), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.