CVE-2025-66171

MEDIUMNVD 6.56.5
EchelonGraph scoreMEDIUM confidence

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

Score 6.5 from GitHub Security Advisory (severity: MODERATE) published 2026-05-08. NVD baseline CVSS 6.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3

Also known asEUVD-2025-209741 (ENISA EUVD) · GHSA-5f56-5m8x-gjf9 (GitHub Security Advisories)Source: ENISA EUVD

6.5EG
EchelonGraph verdictMonitorRemediate within your standard update timelines (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 6.5Exploit: None knownExposed services: Not assessed

The CVE record names the fixed release — apply it.

The CloudStack Backup plugin has an improper access logic in versions 4.21.0.0 and 4.22.0.0. Anyone with authenticated user-account access in CloudStack 4.21.0.0+ environments, where this plugin is enabled and have access to specific APIs can create new VMs using backups of any other user of the environment.

Backup plugin users using CloudStack 4.21.0.0+ are recommended to upgrade to CloudStack version 4.22.0.1, which fixes this issue.

CVSS v3
6.5
EG Score
6.5MEDIUMmedium confidence
EG Risk
29
EG Risk 29/100

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)
Severity65% × 45%
Impact severity (EG Severity): CVSS 6.5 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.5% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: The CVE record names the fixed release. Apply it within your standard update timelines.
EPSS PROB
0.5%
EPSS %ILE
45th
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 (6.5): severity, escalated by confirmed exploitation. This CVE's 6.5 is its impact severity (EG Severity), not escalated.

EG Severity
6.5 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.5% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-07). 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 every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.

The CVE record names the fixed release. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (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)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). 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

May 8, 2026

Last Modified

October 7, 2026

Advisory Details (2)

Auto-updated May 9, 2026
Fix named in the CVE record.
Web page

oss-security - CVE-2025-66171: Apache CloudStack: Any user can create a new VM from backups they should not have access to

http://www.openwall.com/lists/oss-security/2026/05/09/2

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 8× in last 7d / 32× 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 its CVE.org record (CNA or CISA ADP). 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). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.

Showing the most recent 100 of 278 rows on record for this CVE, as 98 entries (2 repeats merged).

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. 2 repeat rows among the latest 100 are merged into the row they repeat. The 178 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-13 16:50 UTCEPSS rescoreEPSS 0.5% · 45th percentile
  2. 2026-11-12 16:32 UTCEPSS rescoreEPSS 0.5% · 45th percentile
  3. 2026-11-11 16:36 UTCEPSS rescoreEPSS 0.5% · 45th percentile
  4. 2026-11-10 16:41 UTCEPSS rescoreEPSS 0.5% · 45th percentile
  5. 2026-11-09 16:33 UTCEPSS rescoreEPSS 0.5% · 45th percentile
  6. 2026-11-08 16:37 UTCEPSS rescoreEPSS 0.5% · 45th percentile
  7. 2026-11-07 19:57 UTCGHSA enrichmentGHSA-5f56-5m8x-gjf9 · GitHub severity MODERATE · GitHub CVSS 6.5
  8. 2026-11-07 19:57 UTCEchelonGraph re-scored
  9. 2026-11-07 16:37 UTCEPSS rescoreEPSS 0.5% · 45th percentile
  10. 2026-11-06 16:34 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  11. 2026-11-05 16:35 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  12. 2026-11-04 16:33 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  13. 2026-11-03 16:45 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  14. 2026-11-02 16:43 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  15. 2026-11-01 16:33 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  16. 2026-10-31 16:31 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  17. 2026-10-30 16:33 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  18. 2026-10-29 16:32 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  19. 2026-10-28 16:30 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  20. 2026-10-27 16:30 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  21. 2026-10-26 16:30 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  22. 2026-10-25 16:31 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  23. 2026-10-25 16:09 UTCEchelonGraph re-scored
  24. 2026-10-24 16:31 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  25. 2026-10-23 16:30 UTCEPSS rescoreEPSS 0.5% · 44th percentile
Show 73 more
  1. 2026-10-23 13:00 UTCEchelonGraph re-scored
  2. 2026-10-23 13:00 UTCGHSA enrichmentGHSA-5f56-5m8x-gjf9 · GitHub CVSS 6.5
  3. 2026-10-22 16:33 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  4. 2026-10-21 16:31 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  5. 2026-10-20 16:31 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  6. 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  7. 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  8. 2026-10-18 05:19 UTCEchelonGraph re-scored
  9. 2026-10-17 16:33 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  10. 2026-10-16 16:39 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  11. 2026-10-15 16:31 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  12. 2026-10-14 16:31 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  13. 2026-10-13 16:33 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  14. 2026-10-12 16:48 UTCEchelonGraph re-scored
  15. 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  16. 2026-10-11 20:23 UTCEchelonGraph re-scored
  17. 2026-10-11 18:35 UTCEchelonGraph re-scored
  18. 2026-10-11 15:10 UTCEchelonGraph re-scored
  19. 2026-10-11 13:47 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  20. 2026-10-10 19:59 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  21. 2026-10-09 20:06 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  22. 2026-10-08 17:10 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  23. 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  24. 2026-10-07 09:13 UTCEchelonGraph re-scored
  25. 2026-10-07 09:13 UTCGHSA enrichmentGHSA-5f56-5m8x-gjf9 · GitHub CVSS 6.5
  26. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  27. 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  28. 2026-10-04 23:21 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  29. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  30. 2026-10-01 19:49 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  31. 2026-09-30 22:28 UTCEchelonGraph re-scored
  32. 2026-09-30 22:28 UTCGHSA enrichmentGHSA-5f56-5m8x-gjf9 · GitHub CVSS 6.5
  33. 2026-09-30 15:02 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  34. 2026-09-29 15:20 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  35. 2026-09-28 13:50 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  36. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  37. 2026-09-24 14:02 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  38. 2026-09-23 13:47 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  39. 2026-09-19 15:42 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  40. 2026-09-18 19:27 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  41. 2026-09-17 19:30 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  42. 2026-09-16 14:07 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  43. 2026-09-15 03:10 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  44. 2026-09-13 16:46 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  45. 2026-09-12 15:00 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  46. 2026-09-11 14:52 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  47. 2026-09-11 09:36 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  48. 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  49. 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  50. 2026-09-07 16:00 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  51. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  52. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  53. 2026-09-02 14:11 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  54. 2026-09-01 13:53 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  55. 2026-08-30 19:16 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  56. 2026-08-30 01:21 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  57. 2026-08-28 21:40 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  58. 2026-08-27 14:24 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  59. 2026-08-26 14:45 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  60. 2026-08-25 13:48 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  61. 2026-08-24 14:16 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  62. 2026-08-23 19:26 UTCEchelonGraph re-scored
  63. 2026-08-23 19:26 UTCGHSA enrichmentGHSA-5f56-5m8x-gjf9 · GitHub CVSS 6.5
  64. 2026-08-23 00:18 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  65. 2026-08-21 23:48 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  66. 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  67. 2026-08-19 17:03 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  68. 2026-08-18 13:47 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  69. 2026-08-17 13:46 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  70. 2026-08-17 11:58 UTCEchelonGraph re-scored
  71. 2026-08-17 11:58 UTCGHSA enrichmentGHSA-5f56-5m8x-gjf9 · GitHub CVSS 6.5
  72. 2026-08-16 14:55 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  73. 2026-08-16 04:39 UTCEchelonGraph re-scored

Frequently asked(5)

What is CVE-2025-66171?
CVE-2025-66171 is a medium-severity vulnerability; its CVE record was published on May 8, 2026. The CloudStack Backup plugin has an improper access logic in versions 4.21.0.0 and 4.22.0.0. Anyone with authenticated user-account access in CloudStack 4.21.0.0+ environments, where this plugin is enabled and have access to specific APIs can create new VMs using backups of any other user of the…
When was the CVE record for CVE-2025-66171 published?
The CVE record for CVE-2025-66171 was published on May 8, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of October 7, 2026; the record at its source may have been updated since.
Is CVE-2025-66171 actively exploited?
CVE-2025-66171 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (45th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2025-66171?
CVE-2025-66171 has a CVSS v3 base score of 6.5 (NVD).
How do I remediate CVE-2025-66171?
The CVE record for CVE-2025-66171 names the fix: "Backup plugin users using CloudStack 4.21.0.0+ are recommended to upgrade to CloudStack version 4.22.0.1, which fixes this issue."

Dependency Blast Radius

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