CVE-2009-0478

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 72.0% 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.
  • High exploitation likelihood — EPSS 72%
  • Public exploit code is available (Exploit-DB (verified), epss top5pct, epss high, public exploit)
CISA-KEV: Not listedEPSS PROB: 72%CVSS v2: 5.0Exploit: Exploit-DB (verified) · epss top5pct · epss high · public exploitExposed: 0

A fix is available — apply it.

Squid 2.7 to 2.7.STABLE5, 3.0 to 3.0.STABLE12, and 3.1 to 3.1.0.4 allows remote attackers to cause a denial of service via an HTTP request with an invalid version number, which triggers a reachable assertion in (1) HttpMsg.c and (2) HttpStatusLine.c.

CVSS v2.0 (legacy)
5.0MEDIUMNVD never assigned a CVSS v3 rating to this CVE
EG Score
5.0(low)
EG Risk
56(Track)
EG Risk 56/100SSVC: 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%
Exploitation72% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
72%
EPSS %ILE
99%
KEV
Not listed

Published

February 8, 2009

Last Modified

April 23, 2026

References (24)

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntusquid (2.7.STABLE3-1ubuntu2.1) @ intrepid2026-05-30ubuntu

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

(5 across 5 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
squid—2.7.STABLE3-4.1—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
squid—2.7.STABLE3-4.1—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
squid—2.7.STABLE3-4.1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
squid—2.7.STABLE3-4.1—
Debian:4.0(1)
PackageVulnerable rangeFixed inDependents
squid33.0.PRE5-53.0.PRE5-5+etch1—

Weakness Classification(1)

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

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 2× in last 7d / 7× 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. 2026-08-26 11:43 UTCOSV refresh
  2. 2026-08-25 13:43 UTCEPSS rescore
  3. 2026-08-19 16:58 UTCEPSS rescore
  4. 2026-08-15 01:24 UTCEPSS rescore
  5. 2026-08-10 00:40 UTCOSV refresh
  6. 2026-08-06 13:41 UTCEPSS rescore
  7. 2026-07-30 16:22 UTCEPSS rescore
  8. 2026-07-26 13:37 UTCEG score recompute▲ 5.00
  9. 2026-07-25 14:12 UTCEPSS rescore
  10. 2026-07-25 01:41 UTCOSV refresh
  11. 2026-07-24 14:12 UTCEPSS rescore
  12. 2026-07-23 00:58 UTCEG score recompute
  13. 2026-07-23 00:36 UTCEG score recompute▼ 6.90
  14. 2026-07-23 00:03 UTCEG score recompute▲ 6.90
  15. 2026-07-22 21:42 UTCEG score recompute
  16. 2026-07-22 14:03 UTCEPSS rescore
  17. 2026-07-21 15:20 UTCEPSS rescore
  18. 2026-07-20 17:03 UTCEPSS rescore
  19. 2026-07-20 17:03 UTCEPSS rescore
  20. 2026-07-15 16:54 UTCEPSS rescore
  21. 2026-07-15 16:54 UTCEPSS rescore
  22. 2026-07-13 22:25 UTCEPSS rescore
  23. 2026-07-13 06:07 UTCEPSS rescore
  24. 2026-07-09 19:04 UTCEPSS rescore
  25. 2026-07-08 15:10 UTCEPSS rescore
Show 54 more
  1. 2026-07-07 20:41 UTCOSV refresh
  2. 2026-07-06 16:23 UTCEPSS rescore
  3. 2026-07-05 02:26 UTCEPSS rescore
  4. 2026-07-05 02:26 UTCEPSS rescore
  5. 2026-07-04 06:27 UTCEPSS rescore
  6. 2026-07-01 15:02 UTCEPSS rescore
  7. 2026-06-28 14:03 UTCEPSS rescore
  8. 2026-06-28 04:52 UTCEPSS rescore
  9. 2026-06-28 04:52 UTCEPSS rescore
  10. 2026-06-25 13:46 UTCEPSS rescore
  11. 2026-06-25 13:46 UTCEPSS rescore
  12. 2026-06-24 14:02 UTCEPSS rescore
  13. 2026-06-24 14:02 UTCEPSS rescore
  14. 2026-06-23 21:29 UTCEPSS rescore
  15. 2026-06-23 21:29 UTCEPSS rescore
  16. 2026-06-21 14:53 UTCEPSS rescore
  17. 2026-06-21 01:56 UTCEPSS rescore
  18. 2026-06-21 01:56 UTCEPSS rescore
  19. 2026-06-19 08:25 UTCOSV refresh
  20. 2026-06-17 17:49 UTCEPSS rescore
  21. 2026-06-17 17:49 UTCEPSS rescore
  22. 2026-06-15 17:44 UTCEPSS rescore
  23. 2026-06-12 23:08 UTCEPSS rescore
  24. 2026-06-12 23:08 UTCEPSS rescore
  25. 2026-06-10 22:14 UTCEPSS rescore
  26. 2026-06-10 13:17 UTCEPSS rescore
  27. 2026-06-08 14:13 UTCEPSS rescore
  28. 2026-06-07 15:22 UTCEPSS rescore
  29. 2026-06-07 15:22 UTCEPSS rescore
  30. 2026-06-06 13:44 UTCEPSS rescore
  31. 2026-06-06 13:44 UTCEPSS rescore
  32. 2026-06-06 13:44 UTCEPSS rescore
  33. 2026-06-05 22:44 UTCEPSS rescore
  34. 2026-06-05 22:44 UTCEPSS rescore
  35. 2026-06-05 06:07 UTCEPSS rescore
  36. 2026-06-01 13:49 UTCEPSS rescore
  37. 2026-06-01 13:49 UTCEPSS rescore
  38. 2026-05-31 00:13 UTCEPSS rescore
  39. 2026-05-31 00:13 UTCEPSS rescore
  40. 2026-05-30 18:22 UTCEG score recompute
  41. 2026-05-30 18:22 UTCVendor advisory
  42. 2026-05-30 18:22 UTCGHSA enrichment
  43. 2026-05-29 13:40 UTCEPSS rescore
  44. 2026-05-28 13:42 UTCEPSS rescore
  45. 2026-05-28 13:42 UTCEPSS rescore
  46. 2026-05-28 13:42 UTCEPSS rescore
  47. 2026-05-26 13:41 UTCEPSS rescore
  48. 2026-05-26 13:41 UTCEPSS rescore
  49. 2026-05-26 07:16 UTCEPSS rescore
  50. 2026-05-26 07:16 UTCEPSS rescore
  51. 2026-05-22 21:15 UTCEPSS rescore
  52. 2026-05-22 21:15 UTCEPSS rescore
  53. 2026-05-22 02:06 UTCOSV refresh
  54. 2026-05-18 21:29 UTCEPSS rescore

Publicly available exploits

(1 reference)

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

  • Exploit-DBEDB-8021✓ verified
    First seen Feb 9, 2009

    Squid < 3.1 5 - HTTP Version Number Parsing Denial of Service

    Open source ↗

Related CVEs(same vendor + same CWE)

Frequently asked(4)

What is CVE-2009-0478?
CVE-2009-0478 is a medium vulnerability published on February 8, 2009. Squid 2.7 to 2.7.STABLE5, 3.0 to 3.0.STABLE12, and 3.1 to 3.1.0.4 allows remote attackers to cause a denial of service via an HTTP request with an invalid version number, which triggers a reachable assertion in (1) HttpMsg.c and (2) HttpStatusLine.c.
When was CVE-2009-0478 disclosed?
CVE-2009-0478 was first published in the National Vulnerability Database on February 8, 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-2009-0478 actively exploited?
CVE-2009-0478 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 72% probability of exploitation in the next 30 days, which ranks it in the top 0.6% of all scored CVEs.
How do I remediate CVE-2009-0478?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2009-0478, 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.

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