CVE-2008-3656

CVE-2008-3656 is a high-severity vulnerability in Ruby-lang Ruby with a CVSS 2.0 base score of 7.8. Its EPSS exploit-prediction score of 70% places it in the 99th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-399.

Key facts

• Severity: High (CVSS 2.0 base score 7.8)
• EPSS exploit prediction: 70% (99th percentile)
• Actively exploited: Not listed in CISA KEV
• Weakness: CWE-399
• Affected product: Ruby-lang Ruby
• Published: 2008-08-13
• Last modified: 2026-06-16

Description

Algorithmic complexity vulnerability in the WEBrick::HTTPUtils.split_header_value function in WEBrick::HTTP::DefaultFileHandler in WEBrick in Ruby 1.8.5 and earlier, 1.8.6 through 1.8.6-p286, 1.8.7 through 1.8.7-p71, and 1.9 through r18423 allows context-dependent attackers to cause a denial of service (CPU consumption) via a crafted HTTP request that is processed by a backtracking regular expression.

Frequently asked questions

What is CVE-2008-3656?

Algorithmic complexity vulnerability in the WEBrick::HTTPUtils.split_header_value function in WEBrick::HTTP::DefaultFileHandler in WEBrick in Ruby 1.8.5 and earlier, 1.8.6 through 1.8.6-p286, 1.8.7 through 1.8.7-p71, and 1.9 through r18423 allows context-dependent attackers to cause a denial of service (CPU consumption) via a crafted HTTP request that is processed by a backtracking regular expression.

How severe is CVE-2008-3656?

CVE-2008-3656 has a CVSS 2.0 base score of 7.8, rated high severity.

Is CVE-2008-3656 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 70% (99th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2008-3656?

CVE-2008-3656 primarily affects Ruby-lang Ruby. In total, 43 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2008-3656?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2008-3656 published?

CVE-2008-3656 was published on 2008-08-13 and last updated on 2026-06-16.

References

• http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=494401
• http://lists.apple.com/archives/security-announce/2009/May/msg00002.html
• http://secunia.com/advisories/31430
• http://secunia.com/advisories/31697
• http://secunia.com/advisories/32165
• http://secunia.com/advisories/32219
• http://secunia.com/advisories/32255
• http://secunia.com/advisories/32256
• http://secunia.com/advisories/32371
• http://secunia.com/advisories/33178
• http://secunia.com/advisories/35074
• http://security.gentoo.org/glsa/glsa-200812-17.xml
• http://support.apple.com/kb/HT3549
• http://support.avaya.com/elmodocs2/security/ASA-2008-424.htm
• http://wiki.rpath.com/wiki/Advisories:rPSA-2008-0264
• http://www.debian.org/security/2008/dsa-1651
• http://www.debian.org/security/2008/dsa-1652
• http://www.redhat.com/support/errata/RHSA-2008-0897.html
• http://www.ruby-lang.org/en/news/2008/08/08/multiple-vulnerabilities-in-ruby/
• http://www.securityfocus.com/archive/1/495884/100/0/threaded
• http://www.securityfocus.com/bid/30644
• http://www.securitytracker.com/id?1020654
• http://www.us-cert.gov/cas/techalerts/TA09-133A.html
• http://www.vupen.com/english/advisories/2008/2334
• http://www.vupen.com/english/advisories/2009/1297
• https://exchange.xforce.ibmcloud.com/vulnerabilities/44371
• https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A9682
• https://usn.ubuntu.com/651-1/
• https://www.redhat.com/archives/fedora-package-announce/2008-October/msg00259.html
• https://www.redhat.com/archives/fedora-package-announce/2008-October/msg00299.html

Affected products (43)

• cpe:2.3:a:ruby-lang:ruby:*:*:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.6.8:*:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.0:*:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.1:*:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.1:-9:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.2:*:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.2:preview2:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.2:preview3:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.2:preview4:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.3:*:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.3:preview1:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.3:preview2:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.3:preview3:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.4:*:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.4:preview1:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.4:preview2:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.4:preview3:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.5:p11:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.5:p113:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.5:p115:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.5:p12:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.5:p2:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.5:p35:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.5:preview1:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.5:preview2:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.5:preview3:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.5:preview4:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.5:preview5:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.6:*:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.6:p110:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.6:p114:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.6:preview1:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.6:preview2:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.6:preview3:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.7:*:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.7:p17:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.7:p22:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.7:p71:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.7:preview1:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:1.8.7:preview2:*:*:*:*:*:*

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Other CWE-399 (Resource Management Errors) vulnerabilities

• CVE-2015-8104 — Critical (CVSS 10.0): The KVM subsystem in the Linux kernel through 4.2.6, and Xen 4.3.x through 4.6.x, allows guest OS users to cause a…
• CVE-2015-0339 — Critical (CVSS 10.0): Adobe Flash Player before 13.0.0.277 and 14.x through 17.x before 17.0.0.134 on Windows and OS X and before…
• CVE-2015-0335 — Critical (CVSS 10.0): Adobe Flash Player before 13.0.0.277 and 14.x through 17.x before 17.0.0.134 on Windows and OS X and before…
• CVE-2015-0333 — Critical (CVSS 10.0): Adobe Flash Player before 13.0.0.277 and 14.x through 17.x before 17.0.0.134 on Windows and OS X and before…
• CVE-2014-4121 — Critical (CVSS 10.0): Microsoft .NET Framework 2.0 SP2, 3.5, 3.5.1, 4, 4.5, 4.5.1, and 4.5.2 does not properly parse internationalized…
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