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.
Conclusion & alert: CVE-2008-3656 is rated High Exploit Risk (84.9/100): CVSS High severity, with high exploitation likelihood (EPSS 79.33%, 99th percentile). Core evidence: 2 public exploit reference(s) are indexed (Exploit-DB). EPSS rose +4.04% over the last day, indicating growing attacker interest. Mandatory action: Public exploits are available—assess exposure, apply mitigations, and prioritize patching.
Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.
| EDB-ID | Source | Kind | Published | Link |
|---|---|---|---|---|
| 32222 | exploit_db | edb | 2008-08-11 | Exploit-DB ↗ |
| — | nvd_ref | exploit_tag | Exploit-DB ↗ |
EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).
| # | Date | Old EPSS score | New EPSS score | Delta (New - Old) |
|---|---|---|---|---|
| 1 | 2026-06-03 | 75.29% | 79.33% | +4.04% |
| 2 | 2026-06-01 | 65.09% | 75.29% | +10.20% |
| 3 | 2026-04-14 | — | 65.09% | — |
Full EPSS history (34 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 7.8 | 2.0 | HIGH |
|
10.0 | 6.9 | [email protected] |
| vendor | priority | summary | link |
|---|---|---|---|
gentoo
|
normal | CVE-2008-3656: 1 GLSA(s) (200812-17), 1 atom(s) (dev-lang/ruby); latest impact normal. | https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2008-3656 |
redhat
|
medium | — | https://access.redhat.com/security/cve/CVE-2008-3656 |
ubuntu
|
medium | CVE-2008-3656 medium priority: Ubuntu including 2 source packages (ruby1.8, ruby1.9), 24 status rows across 12 suites (dapper, feisty, gutsy, hardy, intrepid, jaunty, karmic, lucid, maverick, natty, oneiric, upstream): released 10, not-affected 7, ignored 4, DNE 3. | https://ubuntu.com/security/CVE-2008-3656 |
| Vendor | Product | Version | Raw CPE |
|---|---|---|---|
| ruby-lang | ruby | <= 1.8.5 | cpe:2.3:a:ruby-lang:ruby:*:*:*:*:*:*:*:* |
| ruby-lang | ruby | 1.6.8 | cpe:2.3:a:ruby-lang:ruby:1.6.8:*:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.0 | cpe:2.3:a:ruby-lang:ruby:1.8.0:*:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.1 | cpe:2.3:a:ruby-lang:ruby:1.8.1:*:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.1 | cpe:2.3:a:ruby-lang:ruby:1.8.1:-9:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.2 | cpe:2.3:a:ruby-lang:ruby:1.8.2:*:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.2 | cpe:2.3:a:ruby-lang:ruby:1.8.2:preview2:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.2 | cpe:2.3:a:ruby-lang:ruby:1.8.2:preview3:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.2 | cpe:2.3:a:ruby-lang:ruby:1.8.2:preview4:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.3 | cpe:2.3:a:ruby-lang:ruby:1.8.3:*:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.3 | cpe:2.3:a:ruby-lang:ruby:1.8.3:preview1:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.3 | cpe:2.3:a:ruby-lang:ruby:1.8.3:preview2:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.3 | cpe:2.3:a:ruby-lang:ruby:1.8.3:preview3:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.4 | cpe:2.3:a:ruby-lang:ruby:1.8.4:*:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.4 | cpe:2.3:a:ruby-lang:ruby:1.8.4:preview1:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.4 | cpe:2.3:a:ruby-lang:ruby:1.8.4:preview2:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.4 | cpe:2.3:a:ruby-lang:ruby:1.8.4:preview3:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.5 | cpe:2.3:a:ruby-lang:ruby:1.8.5:p11:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.5 | cpe:2.3:a:ruby-lang:ruby:1.8.5:p113:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.5 | cpe:2.3:a:ruby-lang:ruby:1.8.5:p115:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.5 | cpe:2.3:a:ruby-lang:ruby:1.8.5:p12:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.5 | cpe:2.3:a:ruby-lang:ruby:1.8.5:p2:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.5 | cpe:2.3:a:ruby-lang:ruby:1.8.5:p35:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.5 | cpe:2.3:a:ruby-lang:ruby:1.8.5:preview1:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.5 | cpe:2.3:a:ruby-lang:ruby:1.8.5:preview2:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.5 | cpe:2.3:a:ruby-lang:ruby:1.8.5:preview3:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.5 | cpe:2.3:a:ruby-lang:ruby:1.8.5:preview4:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.5 | cpe:2.3:a:ruby-lang:ruby:1.8.5:preview5:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.6 | cpe:2.3:a:ruby-lang:ruby:1.8.6:*:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.6 | cpe:2.3:a:ruby-lang:ruby:1.8.6:p110:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.6 | cpe:2.3:a:ruby-lang:ruby:1.8.6:p114:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.6 | cpe:2.3:a:ruby-lang:ruby:1.8.6:preview1:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.6 | cpe:2.3:a:ruby-lang:ruby:1.8.6:preview2:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.6 | cpe:2.3:a:ruby-lang:ruby:1.8.6:preview3:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.7 | cpe:2.3:a:ruby-lang:ruby:1.8.7:*:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.7 | cpe:2.3:a:ruby-lang:ruby:1.8.7:p17:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.7 | cpe:2.3:a:ruby-lang:ruby:1.8.7:p22:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.7 | cpe:2.3:a:ruby-lang:ruby:1.8.7:p71:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.7 | cpe:2.3:a:ruby-lang:ruby:1.8.7:preview1:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.7 | cpe:2.3:a:ruby-lang:ruby:1.8.7:preview2:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.7 | cpe:2.3:a:ruby-lang:ruby:1.8.7:preview3:*:*:*:*:*:* |
| ruby-lang | ruby | 1.8.7 | cpe:2.3:a:ruby-lang:ruby:1.8.7:preview4:*:*:*:*:*:* |
| ruby-lang | ruby | 1.9.0 | cpe:2.3:a:ruby-lang:ruby:1.9.0:*:*:*:*:*:*:* |