CVE-2008-1891

MEDIUMCVSS v2 · 5.05.0—
EchelonGraph scoreLOW confidence

This CVE was only ever scored under CVSS v2.0. NVD CVSS v2.0 base 5.0 — v2 rates that MEDIUM (v2 bands: LOW 0.0–3.9 / MEDIUM 4.0–6.9 / HIGH 7.0–10.0; v2 has no CRITICAL band). Vector AV:N/AC:L/Au:N/C:P/I:N/A:N. 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 2.8% exploitation probability in the next 30 days, which is reflected in EG Risk but does not lift the v2 base. Confidence: LOW.

Triggered by: NVD CVSS v2.0 (legacy fallback)
Sources: EPSS, NVD CVSS v2.0
5.0EG
EchelonGraph verdictMonitorRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 2.8%CVSS v2: 5.0Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Directory traversal vulnerability in WEBrick in Ruby 1.8.4 and earlier, 1.8.5 before 1.8.5-p231, 1.8.6 before 1.8.6-p230, 1.8.7 before 1.8.7-p22, and 1.9.0 before 1.9.0-2, when using NTFS or FAT filesystems, allows remote attackers to read arbitrary CGI files via a trailing (1) + (plus), (2) %2b (encoded plus), (3) . (dot), (4) %2e (encoded dot), or (5) %20 (encoded space) character in the URI, possibly related to the WEBrick::HTTPServlet::FileHandler and WEBrick::HTTPServer.new functionality and the :DocumentRoot option.

CVSS v2.0 (legacy)
5.0MEDIUMNVD never assigned a CVSS v3 rating to this CVE
EG Score
5.0MEDIUMlow confidence
EG Risk
28
EG Risk 28/100

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed (value × EchelonGraph’s weight)
Severity50% × 45%
The EG Score, 5.0 of 10.
Exploitation2.8% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability30% × 15%
EchelonGraph's default before algorithm v3.4: CISA had not published Automatable for this CVE.
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track or Track* or Attend at high (mission-essential systems).
Exploitation none (no KEV listing, exploit record or EPSS ≥ 50%) · Automatable unknown (not published for this CVE) · Technical impact unknown (not published for this CVE). 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
2.8%
EPSS %ILE
86th
KEV
Not listed

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track or Track* or Attend at high (mission-essential systems).

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

Exploitation none (no KEV listing, exploit record or EPSS ≥ 50%) · Automatable unknown (not published for this CVE) · Technical impact unknown (not published for this CVE). 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

Published

April 18, 2008

Last Modified

April 23, 2026

References (11)

Vendor Advisories for CVE-2008-1891(3)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(3)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatruby4-0-main-4.0.0-33.3.hum12026-04-17redhat
redhatruby3-3-main-3.3.10-23.1.hum12026-04-09redhat
redhatruby3-4-main-3.4.8-31.1.hum12026-04-09redhat

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.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 8× 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 82 of 114 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. 18 repeat rows among the latest 100 are merged into the row they repeat. The 32 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-11 13:38 UTCEPSS rescoreEPSS 2.8% · 86th percentile
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  12. 2026-09-29 07:49 UTCEG score recompute
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  1. 2026-08-15 01:24 UTCEPSS rescoreEPSS 2.8% · 85th percentile
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  9. 2026-07-26 13:35 UTCEG score recomputeFirst assessed: 5.0 MEDIUM
  10. 2026-07-25 14:12 UTCEPSS rescoreEPSS 2.8% · 85th percentile
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  13. 2026-07-23 00:56 UTCEG score recompute
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  17. 2026-07-20 17:03 UTCEPSS rescoreEPSS 2.8% · 84th percentile
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Frequently asked(4)

What is CVE-2008-1891?
CVE-2008-1891 is a medium-severity vulnerability; its CVE record was published on April 18, 2008. Directory traversal vulnerability in WEBrick in Ruby 1.8.4 and earlier, 1.8.5 before 1.8.5-p231, 1.8.6 before 1.8.6-p230, 1.8.7 before 1.8.7-p22, and 1.9.0 before 1.9.0-2, when using NTFS or FAT filesystems, allows remote attackers to read arbitrary CGI files via a trailing (1) + (plus), (2) %2b…
When was CVE-2008-1891 made public?
CVE-2008-1891 was made public on April 15, 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 April 18, 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-2008-1891 actively exploited?
CVE-2008-1891 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 2.8% probability of exploitation in the next 30 days (86th percentile of EPSS-scored CVEs).
How do I remediate CVE-2008-1891?
A fix for CVE-2008-1891 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2008-1891 are linked in the Vendor Advisories panel on this page.

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