CVE-2009-2521

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:N/I:N/A:P. 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 85.0% exploitation probability in the next 30 days, which is reflected in EG Risk but does not lift the v2 base. Confidence: LOW.

Sources: epss, nvd_v2
Weaponized
5.0EG
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • 142 internet-exposed hosts are running an affected version right now
  • High exploitation likelihood — EPSS 85%
  • Public exploit code is available (Metasploit, Exploit-DB (verified), epss top5pct, epss high, public exploit)
CISA-KEV: Not listedEPSS PROB: 85%CVSS v2: 5.0Exploit: Metasploit · Exploit-DB (verified) · epss top5pct · epss high · public exploitExposed: 142

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Stack consumption vulnerability in the FTP Service in Microsoft Internet Information Services (IIS) 5.0 through 7.0 allows remote authenticated users to cause a denial of service (daemon crash) via a list (ls) -R command containing a wildcard that references a subdirectory, followed by a .. (dot dot), aka "IIS FTP Service DoS Vulnerability."

Live · internet exposure

142 internet-exposed hosts are running an affected version of CVE-2009-2521 right now.

across 29 countries (United States, China, France, Canada, Korea, Republic of)top: internet_information_services
See the live KEV-Exposure radar →Found passively from public internet-scan data — aggregate, host-redacted.

EchelonGraph is the only CVE feed that fuses live vulnerability intelligence with its own live internet-exposure radar — so you see not just that a CVE is exploited, but how much of the internet is exposed to it right now.

CVSS v2.0 (legacy)
5.0MEDIUMNVD never assigned a CVSS v3 rating to this CVE
EG Score
5.0(low)
EG Risk
61(Track)
EG Risk 61/100SSVC: Track

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
Severity50% × 45%
Exploitation85% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
85%
EPSS %ILE
100%
KEV
Not listed

Published

September 4, 2009

Last Modified

April 23, 2026

References (10)

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 11× in last 7d / 20× 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.

  1. 2026-07-26 13:38 UTCEG score recompute▲ 5.00
  2. 2026-07-25 14:12 UTCEPSS rescore
  3. 2026-07-24 14:12 UTCEPSS rescore
  4. 2026-07-23 00:59 UTCEG score recompute
  5. 2026-07-23 00:37 UTCEG score recompute▼ 8.60
  6. 2026-07-23 00:04 UTCEG score recompute▲ 8.60
  7. 2026-07-22 21:43 UTCEG score recompute
  8. 2026-07-22 14:03 UTCEPSS rescore
  9. 2026-07-21 15:20 UTCEPSS rescore
  10. 2026-07-20 17:03 UTCEPSS rescore
  11. 2026-07-20 17:03 UTCEPSS rescore
  12. 2026-07-16 16:58 UTCEPSS rescore
  13. 2026-07-15 16:54 UTCEPSS rescore
  14. 2026-07-15 16:54 UTCEPSS rescore
  15. 2026-07-13 22:25 UTCEPSS rescore
  16. 2026-07-09 19:04 UTCEPSS rescore
  17. 2026-07-06 02:19 UTCEPSS rescore
  18. 2026-07-06 02:19 UTCEPSS rescore
  19. 2026-07-04 06:27 UTCEPSS rescore
  20. 2026-07-01 15:02 UTCEPSS rescore
  21. 2026-06-27 03:05 UTCEPSS rescore
  22. 2026-06-25 13:46 UTCEPSS rescore
  23. 2026-06-25 13:46 UTCEPSS rescore
  24. 2026-06-23 21:29 UTCEPSS rescore
  25. 2026-06-23 21:29 UTCEPSS rescore
Show 42 more
  1. 2026-06-21 14:53 UTCEPSS rescore
  2. 2026-06-21 01:56 UTCEPSS rescore
  3. 2026-06-21 01:56 UTCEPSS rescore
  4. 2026-06-17 17:49 UTCEPSS rescore
  5. 2026-06-17 17:49 UTCEPSS rescore
  6. 2026-06-16 17:49 UTCEPSS rescore
  7. 2026-06-16 17:49 UTCEPSS rescore
  8. 2026-06-15 17:44 UTCEPSS rescore
  9. 2026-06-14 23:14 UTCEPSS rescore
  10. 2026-06-14 23:14 UTCEPSS rescore
  11. 2026-06-13 22:57 UTCEPSS rescore
  12. 2026-06-12 23:08 UTCEPSS rescore
  13. 2026-06-12 23:08 UTCEPSS rescore
  14. 2026-06-10 22:14 UTCEPSS rescore
  15. 2026-06-10 13:17 UTCEPSS rescore
  16. 2026-06-08 14:13 UTCEPSS rescore
  17. 2026-06-07 15:22 UTCEPSS rescore
  18. 2026-06-07 15:22 UTCEPSS rescore
  19. 2026-06-06 13:44 UTCEPSS rescore
  20. 2026-06-06 13:44 UTCEPSS rescore
  21. 2026-06-06 13:44 UTCEPSS rescore
  22. 2026-06-05 22:44 UTCEPSS rescore
  23. 2026-06-05 22:44 UTCEPSS rescore
  24. 2026-06-05 06:07 UTCEPSS rescore
  25. 2026-06-02 20:10 UTCEPSS rescore
  26. 2026-06-02 20:10 UTCEPSS rescore
  27. 2026-06-01 13:49 UTCEPSS rescore
  28. 2026-06-01 13:49 UTCEPSS rescore
  29. 2026-05-31 00:13 UTCEPSS rescore
  30. 2026-05-31 00:13 UTCEPSS rescore
  31. 2026-05-30 15:28 UTCEG score recompute
  32. 2026-05-30 15:28 UTCGHSA enrichment
  33. 2026-05-29 13:40 UTCEPSS rescore
  34. 2026-05-28 13:42 UTCEPSS rescore
  35. 2026-05-28 13:42 UTCEPSS rescore
  36. 2026-05-28 13:42 UTCEPSS rescore
  37. 2026-05-27 13:38 UTCEPSS rescore
  38. 2026-05-27 13:38 UTCEPSS rescore
  39. 2026-05-24 16:43 UTCEPSS rescore
  40. 2026-05-22 21:15 UTCEPSS rescore
  41. 2026-05-22 21:15 UTCEPSS rescore
  42. 2026-05-18 21:29 UTCEPSS rescore

Publicly available exploits

(3 references)

Working exploit code is in the public domain (1 Metasploit module) (2 Exploit-DB entries). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • Exploit-DBEDB-17476
    First seen Jul 3, 2011

    Microsoft IIS 7.0 FTP Server - Stack Exhaustion Denial of Service (MS09-053) (Metasploit)

    Open source ↗
  • Exploit-DBEDB-9587✓ verified
    First seen Sep 4, 2009

    Microsoft IIS 5.0/6.0 FTP Server - Stack Exhaustion Denial of Service

    Open source ↗
  • Metasploitauxiliary/dos/windows/ftp/iis_list_exhaustion✓ verified
    First seen Sep 3, 2009

    Microsoft IIS FTP Server LIST Stack Exhaustion

    Open source ↗

Related CVEs(same CWE)

Frequently asked(4)

What is CVE-2009-2521?
CVE-2009-2521 is a medium vulnerability published on September 4, 2009. Stack consumption vulnerability in the FTP Service in Microsoft Internet Information Services (IIS) 5.0 through 7.0 allows remote authenticated users to cause a denial of service (daemon crash) via a list (ls) -R command containing a wildcard that references a subdirectory, followed by a .. (dot…
When was CVE-2009-2521 disclosed?
CVE-2009-2521 was first published in the National Vulnerability Database on September 4, 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-2009-2521 actively exploited?
CVE-2009-2521 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 85% probability of exploitation in the next 30 days, which ranks it in the top 0.3% of all scored CVEs.
How do I remediate CVE-2009-2521?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2009-2521, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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