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CVE-2008-3656

75
FAUCET Score

CVE-2008-3656 is an algorithmic complexity vulnerability in the WEBrick component of Ruby versions 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. An unauthenticated attacker can exploit this via a crafted HTTP request, leading to a denial of service (CPU consumption) due to a backtracking regular expression. With a CVSS score of 7.8 and an EPSS score indicating high exploitability, this vulnerability is considered severe. While not on the KEV catalog, public exploit modules exist for Metasploit and ExploitDB, though there is no evidence of active exploitation or significant community discussion.

Impacted Technologies

VendorProductVersion(s)CPE
<= 1.8.5CPE matchmatch criteria
cpe:2.3:a:ruby-lang:ruby:*:*:*:*:*:*:*:*
1.6.8CPE matchmatch criteria
cpe:2.3:a:ruby-lang:ruby:1.6.8:*:*:*:*:*:*:*
1.8.0CPE matchmatch criteria
cpe:2.3:a:ruby-lang:ruby:1.8.0:*:*:*:*:*:*:*
1.8.1CPE matchmatch criteria
cpe:2.3:a:ruby-lang:ruby:1.8.1:*:*:*:*:*:*:*
1.8.1CPE matchmatch criteria
cpe:2.3:a:ruby-lang:ruby:1.8.1:-9:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 2.0

7.8HIGH

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

Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
COMPLETE
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Exploitability Score
10.0
Impact Score
6.9
CvssVersion
2.0

Exploit Intelligence

EPSS Score
70.20%
Probability of exploitation in next 30 days
EPSS Percentile
99.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
Metasploit: Ruby WEBrick::HTTP::DefaultFileHandler DoS · Aug 8, 2008
ExploitDB: EDB-32222 · Aug 11, 2008
This CVE's current EPSS score of 0.7020 is in the 99th percentile among its peer group of 51,506 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 4Fixed in: ruby-0:1.8.1-7.el4_7.1
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 5Fixed in: ruby-0:1.8.5-5.el5_2.5
View patch

Vendor Advisories (1)

redhatCVE-2008-3656Moderate

ruby: WEBrick DoS vulnerability (CPU consumption)

Aug 8, 2008

References

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