CVE-2009-4021

MEDIUMCVSS v2 · 4.94.9—
EchelonGraph scoreLOW confidence

This CVE was only ever scored under CVSS v2.0. NVD CVSS v2.0 base 4.9 — 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:L/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 0.4% 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_v2
4.9EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS v2: 4.9Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

The fuse_direct_io function in fs/fuse/file.c in the fuse subsystem in the Linux kernel before 2.6.32-rc7 might allow attackers to cause a denial of service (invalid pointer dereference and OOPS) via vectors possibly related to a memory-consumption attack.

CVSS v2.0 (legacy)
4.9MEDIUMNVD never assigned a CVSS v3 rating to this CVE
EG Score
4.9MEDIUMlow confidence
EG Risk
27
EG Risk 27/100CISA SSVC

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
Severity49% × 45%
Exploitation0% × 40%
Automatability30% × 15%
CISA SSVC: Track at low or medium mission impact; Track or Track* or Attend at high (mission-essential systems).
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
0.4%
EPSS %ILE
33rd
KEV
Not listed

CISA SSVCTrack 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). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

November 25, 2009

Last Modified

April 23, 2026

References (40)

Vendor Advisories for CVE-2009-4021(2)

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
ubuntulinux-image-2.6.24-27-hppa64 (2.6.24-27.65) @ hardy2026-05-30ubuntu
redhatkernel-rt-0:2.6.24.7-146.el5rt2010-01-21redhat
redhatkernel-0:2.6.18-164.11.1.el52010-01-19redhat

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
linux-2.62.6.18.dfsg.1-12 ... 2.6.18.dfsg.1-26etch1 (38 versions)
  • every version up to 2.6.18.dfsg.1-26etch2: fixed in 2.6.18.dfsg.1-26etch2
—
linux-2.6.242.6.24-5~etchnhalf.1 ... 2.6.24-6~etchnhalf.9etch2 (15 versions)
  • every version up to 2.6.24-6~etchnhalf.9etch3: fixed in 2.6.24-6~etchnhalf.9etch3
—

Additional Vendor Advisories

(1)

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 6× in last 7d / 16× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

Showing the most recent 100 of 133 total refreshes for this CVE.

  1. 2026-10-09 20:00 UTCEPSS rescore
  2. 2026-10-08 16:33 UTCEPSS rescore
  3. 2026-10-07 23:37 UTCEPSS rescore
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  7. 2026-09-30 14:58 UTCEPSS rescore
  8. 2026-09-29 08:01 UTCEG score recompute
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  1. 2026-08-08 16:31 UTCEPSS rescore
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  3. 2026-08-03 10:28 UTCEPSS rescore
  4. 2026-07-30 16:22 UTCEPSS rescore
  5. 2026-07-30 01:26 UTCEPSS rescore
  6. 2026-07-26 13:39 UTCEG score recompute▲ 4.90
  7. 2026-07-25 14:12 UTCEPSS rescore
  8. 2026-07-24 14:12 UTCEPSS rescore
  9. 2026-07-23 14:14 UTCEPSS rescore
  10. 2026-07-23 01:00 UTCEG score recompute
  11. 2026-07-23 00:37 UTCEG score recompute
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  13. 2026-07-22 21:43 UTCEG score recompute
  14. 2026-07-22 14:03 UTCEPSS rescore
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  20. 2026-07-15 16:54 UTCEPSS rescore
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  25. 2026-07-11 08:22 UTCEPSS rescore
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  27. 2026-07-09 19:04 UTCEPSS rescore
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  44. 2026-06-24 14:02 UTCEPSS rescore
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  75. 2026-06-05 22:44 UTCEPSS rescore

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Frequently asked(4)

What is CVE-2009-4021?
CVE-2009-4021 is a medium vulnerability published on November 25, 2009. The fusedirectio function in fs/fuse/file.c in the fuse subsystem in the Linux kernel before 2.6.32-rc7 might allow attackers to cause a denial of service (invalid pointer dereference and OOPS) via vectors possibly related to a memory-consumption attack.
When was CVE-2009-4021 disclosed?
CVE-2009-4021 was first published on November 25, 2009, with the most recent update on April 23, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2009-4021 actively exploited?
CVE-2009-4021 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (33rd percentile of EPSS-scored CVEs).
How do I remediate CVE-2009-4021?
A fix for CVE-2009-4021 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2009-4021 are linked in the Vendor Advisories panel on this page.

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