CVE-2008-3656

HIGHCVSS v2 · 7.87.8
EchelonGraph scoreLOW confidence

“—” beside the score: it is equal to NVD's CVSS v2 base score.

This CVE was only ever scored under CVSS v2.0. NVD CVSS v2.0 base 7.8 — NVD rates that HIGH (NVD's v2 bands: LOW 0.0–3.9 / MEDIUM 4.0–6.9 / HIGH 7.0–10.0; no CRITICAL band). Vector AV:N/AC:L/Au:N/C:N/I:N/A:C. CVSS v2 is an older, coarser metric than v3.1/v4.0 (no Scope, no User Interaction, no Attack Requirements), so it is not directly comparable to a v3 or v4 score. NVD has never re-scored this record under v3. EPSS predicts 70% exploitation probability in the next 30 days; it does not lift the v2 base. EPSS sets EG Risk's exploitation input. Confidence: LOW.

Triggered by: NVD CVSS v2.0 (legacy fallback)
Sources: NVD CVSS v2.0
Weaponized
7.8EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • High exploitation likelihood — EPSS 70%
  • Public exploit code is available (Metasploit, Exploit-DB, marked verified by Exploit-DB)
CISA-KEV: Not listedEPSS PROB: 70%CVSS v2: 7.8Exploit: Metasploit · Exploit-DB (verified)Exposed services: Not assessed

A fix is available — apply it.

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.

CVSS v2.0 (legacy)
7.8HIGHNVD never assigned a CVSS v3 rating to this CVE
EG Score
7.8HIGHlow confidence
EG Risk
63
EG Risk 63/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity78% × 45%
Impact severity (EG Severity): CVSS 7.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation70% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's BOD 26-04 default: no one has published Automatable for this CVE, and CISA treats it as “no” for a CVE not in KEV.
SSVC (CISA's decision table, applied by EchelonGraph): Track at low, Track* at medium and Attend at high mission impact.
Exploitation public PoC (exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
70%
EPSS %ILE
99th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (7.8): severity, escalated by confirmed exploitation. This CVE's 7.8 is its impact severity (EG Severity), not escalated.

EG Severity
7.8 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v2.0 · CVSS v2.0AV:N/AC:L/Au:N/C:N/I:N/A:C
EG Likelihood
70% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-17). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track* at medium mission impactTrack at low, Track* at medium and Attend at high mission impact.CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low, Track* at medium and Attend at high mission impact.

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

August 13, 2008

Last Modified

April 23, 2026

References (30)

15 of 30 shown · show the other 15

Patch Availability(5)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntulibruby1.8 (1.8.6.111-2ubuntu1.2) @ hardy2026-05-30ubuntu
redhatruby4-0-main-4.0.0-33.3.hum12026-04-17redhat
redhatruby3-4-main-3.4.8-31.1.hum12026-04-09redhat
redhatruby3-3-main-3.3.10-23.1.hum12026-04-09redhat
redhatruby-0:1.8.5-5.el5_2.52008-10-21redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(2 across 1 ecosystem)
Debian:4.0(2)
PackageVulnerable rangeFix by version rangeDependents
ruby1.81.8.5-4, 1.8.5-4etch1, 1.8.5-4etch2
  • every version up to 1.8.5-4etch3: fixed in 1.8.5-4etch3
—
ruby1.91.9.0+20060609-1, 1.9.0+20060609-1etch1, 1.9.0+20060609-1etch2
  • every version up to 1.9.0+20060609-1etch3: fixed in 1.9.0+20060609-1etch3
—

Additional Vendor Advisories

(2)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 5× in last 7d / 18× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 79 of 82 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 21 repeat rows among the latest 100 are merged into the row they repeat. The 3 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-21 16:25 UTCEPSS rescoreEPSS 70% · 99th percentile
  2. 2026-10-20 16:25 UTCEPSS rescoreEPSS 70% · 99th percentile
  3. 2026-10-19 16:25 UTCEPSS rescoreEPSS 70% · 99th percentile
  4. 2026-10-18 11:50 UTCEG score recompute
  5. 2026-10-16 16:25 UTCEPSS rescoreEPSS 70% · 99th percentile
  6. 2026-10-14 16:26 UTCEPSS rescoreEPSS 70% · 99th percentile
  7. 2026-10-13 16:26 UTCEPSS rescoreEPSS 70% · 99th percentile
  8. 2026-10-12 21:51 UTCEG score recompute
  9. 2026-10-12 01:59 UTCEG score recompute
  10. 2026-10-10 19:53 UTCEPSS rescoreEPSS 70% · 99th percentile
  11. 2026-10-08 16:33 UTCEPSS rescoreEPSS 70% · 99th percentile
  12. 2026-10-07 23:37 UTCEPSS rescoreEPSS 70% · 99th percentile
  13. 2026-10-06 15:09 UTCEPSS rescoreEPSS 70% · 99th percentile
  14. 2026-10-03 14:20 UTCEPSS rescoreEPSS 70% · 99th percentile
  15. 2026-10-01 19:42 UTCEPSS rescoreEPSS 70% · 99th percentile
  16. 2026-09-30 14:57 UTCEPSS rescoreEPSS 70% · 99th percentile
  17. 2026-09-29 07:51 UTCEG score recompute
  18. 2026-09-26 15:52 UTCEPSS rescoreEPSS 70% · 99th percentile
  19. 2026-09-18 19:20 UTCEPSS rescoreEPSS 70% · 99th percentile
  20. 2026-09-17 19:20 UTCEPSS rescoreEPSS 70% · 99th percentile
  21. 2026-09-13 16:40 UTCEPSS rescoreEPSS 70% · 99th percentile
  22. 2026-09-12 14:54 UTCEPSS rescoreEPSS 70% · 99th percentile
  23. 2026-09-10 09:24 UTCEPSS rescoreEPSS 70% · 99th percentile
  24. 2026-09-06 13:41 UTCEPSS rescoreEPSS 70% · 99th percentile
  25. 2026-09-05 15:22 UTCEPSS rescoreEPSS 70% · 99th percentile
Show 54 more
  1. 2026-09-04 13:55 UTCEPSS rescoreEPSS 70% · 99th percentile
  2. 2026-09-04 04:59 UTCEPSS rescoreEPSS 70% · 99th percentile
  3. 2026-08-28 21:34 UTCEPSS rescoreEPSS 70% · 99th percentile
  4. 2026-08-15 01:24 UTCEPSS rescoreEPSS 70% · 99th percentile
  5. 2026-08-07 16:21 UTCEPSS rescoreEPSS 70% · 99th percentile
  6. 2026-08-05 19:11 UTCEPSS rescoreEPSS 70% · 99th percentile
  7. 2026-07-30 01:25 UTCEPSS rescoreEPSS 70% · 99th percentile
  8. 2026-07-26 13:36 UTCEG score recomputeAssessed again: 7.8 HIGH
  9. 2026-07-25 14:12 UTCEPSS rescoreEPSS 70% · 99th percentile
  10. 2026-07-24 14:12 UTCEPSS rescoreEPSS 70% · 99th percentile
  11. 2026-07-23 00:56 UTCEG score recompute
  12. 2026-07-23 00:35 UTCEG score recompute▼ 6.60
  13. 2026-07-23 00:01 UTCEG score recomputeFirst assessed: 6.6 MEDIUM
  14. 2026-07-22 21:40 UTCEG score recompute
  15. 2026-07-20 17:03 UTCEPSS rescoreEPSS 70% · 99th percentile
  16. 2026-07-15 16:54 UTCEPSS rescoreEPSS 70% · 99th percentile
  17. 2026-07-15 01:55 UTCEPSS rescoreEPSS 70% · 99th percentile
  18. 2026-07-09 19:04 UTCEPSS rescoreEPSS 70% · 99th percentile
  19. 2026-07-08 15:09 UTCEPSS rescoreEPSS 70% · 99th percentile
  20. 2026-07-04 06:27 UTCEPSS rescoreEPSS 70% · 99th percentile
  21. 2026-07-02 14:00 UTCEPSS rescoreEPSS 70% · 99th percentile
  22. 2026-07-01 15:02 UTCEPSS rescoreEPSS 70% · 99th percentile
  23. 2026-06-29 14:02 UTCEPSS rescoreEPSS 70% · 99th percentile
  24. 2026-06-28 04:52 UTCEPSS rescoreEPSS 70% · 99th percentile
  25. 2026-06-25 13:46 UTCEPSS rescoreEPSS 70% · 99th percentile
  26. 2026-06-24 14:02 UTCEPSS rescoreEPSS 70% · 99th percentile
  27. 2026-06-23 21:29 UTCEPSS rescoreEPSS 70% · 99th percentile
  28. 2026-06-21 14:53 UTCEPSS rescoreEPSS 70% · 99th percentile
  29. 2026-06-18 17:49 UTCEPSS rescoreEPSS 70% · 99th percentile
  30. 2026-06-17 17:49 UTCEPSS rescoreEPSS 70% · 99th percentile
  31. 2026-06-16 17:49 UTCEPSS rescoreEPSS 70% · 99th percentile
  32. 2026-06-15 17:44 UTCEPSS rescoreEPSS 70% · 99th percentile
  33. 2026-06-13 22:57 UTCEPSS rescoreEPSS 79% · 99th percentile
  34. 2026-06-12 23:08 UTCEPSS rescoreEPSS 79% · 99th percentile
  35. 2026-06-11 13:56 UTCEPSS rescoreEPSS 79% · 99th percentile
  36. 2026-06-10 22:14 UTCEPSS rescoreEPSS 79% · 99th percentile
  37. 2026-06-10 13:17 UTCEPSS rescoreEPSS 79% · 99th percentile
  38. 2026-06-08 14:13 UTCEPSS rescoreEPSS 79% · 99th percentile
  39. 2026-06-07 15:22 UTCEPSS rescoreEPSS 79% · 99th percentile
  40. 2026-06-06 13:44 UTCEPSS rescoreEPSS 79% · 99th percentile
  41. 2026-06-05 22:44 UTCEPSS rescoreEPSS 79% · 99th percentile
  42. 2026-06-05 06:07 UTCEPSS rescoreEPSS 79% · 99th percentile
  43. 2026-06-04 13:09 UTCEPSS rescoreEPSS 79% · 99th percentile
  44. 2026-06-02 20:10 UTCEPSS rescoreEPSS 75% · 98th percentile
  45. 2026-06-01 13:49 UTCEPSS rescoreEPSS 75% · 98th percentile
  46. 2026-05-31 00:13 UTCEPSS rescoreEPSS 65% · 98th percentile
  47. 2026-05-30 20:40 UTCEG score recompute
  48. 2026-05-30 20:40 UTCVendor advisory
  49. 2026-05-30 20:40 UTCGHSA enrichmentGHSA-823x-6r7f-v9x6 · GitHub severity HIGH
  50. 2026-05-29 13:40 UTCEPSS rescoreEPSS 65% · 98th percentile
  51. 2026-05-27 13:37 UTCEPSS rescoreEPSS 65% · 98th percentile
  52. 2026-05-26 07:16 UTCEPSS rescoreEPSS 65% · 98th percentile
  53. 2026-05-24 16:43 UTCEPSS rescoreEPSS 65% · 98th percentile
  54. 2026-05-22 21:15 UTCEPSS rescoreEPSS 65% · 98th percentile

Publicly available exploits

(2 references)

Public exploit code is referenced for this CVE (1 Metasploit module, 1 Exploit-DB entry). Defenders should treat patch urgency accordingly.

  • Metasploitauxiliary/dos/http/webrick_regex✓ verified
    Published Oct 17, 2008

    Ruby WEBrick::HTTP::DefaultFileHandler DoS

    Open source ↗
  • Exploit-DBEDB-32222✓ verified
    Published Aug 11, 2008

    Ruby 1.9 - 'WEBrick::HTTP::DefaultFileHandler' Crafted HTTP Request Denial of Service

    Open source ↗

Frequently asked(4)

What is CVE-2008-3656?
CVE-2008-3656 is a high-severity vulnerability; its CVE record was published on August 13, 2008. Algorithmic complexity vulnerability in the WEBrick::HTTPUtils.splitheadervalue 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…
When was CVE-2008-3656 made public?
CVE-2008-3656 was made public on August 8, 2008: that is the date its CVE record's CNA, MITRE Corporation, gives for when the vulnerability was made public. The CVE record itself was published on August 13, 2008. EchelonGraph's copy of the record carries a last-modified date of April 23, 2026; the record at its source may have been updated since.
Is CVE-2008-3656 actively exploited?
CVE-2008-3656 is not currently on CISA's Known Exploited Vulnerabilities catalog. EchelonGraph's EG-KEV model places it in Tier 2 (Weaponized), which is not evidence of exploitation: a Metasploit module exists for it, and Exploit-DB marks a public exploit for it as verified. EchelonGraph does not test whether exploit code works. FIRST EPSS estimates a 70% probability of exploitation in the next 30 days (99th percentile of EPSS-scored CVEs).
How do I remediate CVE-2008-3656?
A fix for CVE-2008-3656 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2008-3656 are linked in the Vendor Advisories panel on this page.

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