CVE-2026-25199

CRITICALNVD 9.19.1—
EchelonGraph scoreMEDIUM confidence

Score 9.1 from GitHub Security Advisory (severity: CRITICAL) published 2026-05-08. NVD baseline CVSS 9.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
9.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 9.1Exploit: None knownExposed: 0

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

Instances deployed via the Proxmox extension allow unauthorized access to instances belonging to other tenants.

This issue affects Apache CloudStack: from 4.21.0.0 through 4.22.0.0.

The Proxmox extension for CloudStack improperly uses a user-editable instance setting, proxmox_vmid, to associate CloudStack instances with Proxmox virtual machines. Because this value is not restricted or validated against tenant ownership and Proxmox VM IDs are predictable, a non-privileged attacker can modify the setting to reference a VM belonging to another account. This allows unauthorized cross-tenant access and enables full control over the targeted VM, including starting, stopping, and destroying the virtual machine.

Users are recommended to upgrade to version 4.22.0.1, which fixes this issue.

As a workaround for the existing installations, editing of the proxmox_vmid instance detail by users can be prevented by adding this detail name to the global configuration parameter - user.vm.denied.details.

CVSS v3
9.1
EG Score
9.1(medium)
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
Severity91% × 45%
Exploitation1% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
41%
KEV
Not listed

Published

May 8, 2026

Last Modified

May 9, 2026

Advisory Details (2)

Auto-updated Aug 1, 2026
No patch confirmed yet.
generic

oss-security - CVE-2026-25199: Apache CloudStack: Proxmox Extension Allows Unauthorized Cross-Tenant Instance Access

http://www.openwall.com/lists/oss-security/2026/05/09/7
generic
https://lists.apache.org/thread/n8mt5b7wkpysstb8w7rr9f02kc5cq2xm

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 6× in last 7d / 31× 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 308 total refreshes for this CVE.

  1. 2026-09-13 16:47 UTCEPSS rescore
  2. 2026-09-12 15:01 UTCEPSS rescore
  3. 2026-09-11 15:10 UTCOSV refresh
  4. 2026-09-11 14:52 UTCEPSS rescore
  5. 2026-09-10 09:34 UTCEPSS rescore
  6. 2026-09-08 22:00 UTCEPSS rescore
  7. 2026-09-07 16:01 UTCEPSS rescore
  8. 2026-09-06 13:47 UTCEPSS rescore
  9. 2026-09-06 13:47 UTCEPSS rescore
  10. 2026-09-04 05:06 UTCEPSS rescore
  11. 2026-09-02 14:11 UTCEPSS rescore
  12. 2026-09-01 13:53 UTCEPSS rescore
  13. 2026-09-01 04:39 UTCEPSS rescore
  14. 2026-08-30 19:17 UTCEPSS rescore
  15. 2026-08-30 01:22 UTCEPSS rescore
  16. 2026-08-28 21:41 UTCEPSS rescore
  17. 2026-08-27 14:25 UTCEPSS rescore
  18. 2026-08-26 14:46 UTCEPSS rescore
  19. 2026-08-25 13:48 UTCEPSS rescore
  20. 2026-08-23 19:26 UTCEG score recompute
  21. 2026-08-23 19:26 UTCGHSA enrichment
  22. 2026-08-23 00:19 UTCEPSS rescore
  23. 2026-08-21 23:49 UTCEPSS rescore
  24. 2026-08-20 22:55 UTCEPSS rescore
  25. 2026-08-19 17:03 UTCEPSS rescore
Show 75 more
  1. 2026-08-18 13:48 UTCEPSS rescore
  2. 2026-08-17 13:47 UTCEPSS rescore
  3. 2026-08-17 11:58 UTCEG score recompute
  4. 2026-08-17 11:58 UTCGHSA enrichment
  5. 2026-08-16 14:56 UTCEPSS rescore
  6. 2026-08-16 09:12 UTCGHSA enrichment
  7. 2026-08-16 04:39 UTCEG score recompute
  8. 2026-08-16 04:39 UTCGHSA enrichment
  9. 2026-08-16 02:14 UTCEPSS rescore
  10. 2026-08-15 01:30 UTCEPSS rescore
  11. 2026-08-15 01:07 UTCGHSA enrichment
  12. 2026-08-14 20:45 UTCGHSA enrichment
  13. 2026-08-14 16:22 UTCGHSA enrichment
  14. 2026-08-14 12:00 UTCGHSA enrichment
  15. 2026-08-14 07:37 UTCGHSA enrichment
  16. 2026-08-14 03:14 UTCEG score recompute
  17. 2026-08-14 03:14 UTCGHSA enrichment
  18. 2026-08-13 22:00 UTCEPSS rescore
  19. 2026-08-13 10:48 UTCGHSA enrichment
  20. 2026-08-13 06:06 UTCGHSA enrichment
  21. 2026-08-13 01:40 UTCGHSA enrichment
  22. 2026-08-12 21:18 UTCGHSA enrichment
  23. 2026-08-12 16:50 UTCEG score recompute
  24. 2026-08-12 16:50 UTCGHSA enrichment
  25. 2026-08-12 13:50 UTCEPSS rescore
  26. 2026-08-12 00:38 UTCGHSA enrichment
  27. 2026-08-11 20:15 UTCGHSA enrichment
  28. 2026-08-11 15:53 UTCEG score recompute
  29. 2026-08-11 15:53 UTCGHSA enrichment
  30. 2026-08-11 13:42 UTCEPSS rescore
  31. 2026-08-11 10:19 UTCGHSA enrichment
  32. 2026-08-11 05:43 UTCGHSA enrichment
  33. 2026-08-11 01:20 UTCEG score recompute
  34. 2026-08-11 01:20 UTCGHSA enrichment
  35. 2026-08-11 00:00 UTCEPSS rescore
  36. 2026-08-10 13:39 UTCGHSA enrichment
  37. 2026-08-10 09:10 UTCGHSA enrichment
  38. 2026-08-10 04:47 UTCGHSA enrichment
  39. 2026-08-10 00:25 UTCGHSA enrichment
  40. 2026-08-09 20:02 UTCGHSA enrichment
  41. 2026-08-09 15:38 UTCEG score recompute
  42. 2026-08-09 15:38 UTCGHSA enrichment
  43. 2026-08-09 13:46 UTCEPSS rescore
  44. 2026-08-09 11:16 UTCGHSA enrichment
  45. 2026-08-09 06:49 UTCGHSA enrichment
  46. 2026-08-09 02:27 UTCEG score recompute
  47. 2026-08-09 02:27 UTCGHSA enrichment
  48. 2026-08-08 16:37 UTCEPSS rescore
  49. 2026-08-08 11:05 UTCGHSA enrichment
  50. 2026-08-08 06:42 UTCGHSA enrichment
  51. 2026-08-08 02:20 UTCGHSA enrichment
  52. 2026-08-07 21:57 UTCGHSA enrichment
  53. 2026-08-07 17:35 UTCEG score recompute
  54. 2026-08-07 17:35 UTCGHSA enrichment
  55. 2026-08-07 13:12 UTCGHSA enrichment
  56. 2026-08-07 08:49 UTCGHSA enrichment
  57. 2026-08-07 01:45 UTCGHSA enrichment
  58. 2026-08-06 21:15 UTCGHSA enrichment
  59. 2026-08-06 16:52 UTCEG score recompute
  60. 2026-08-06 16:52 UTCGHSA enrichment
  61. 2026-08-06 13:46 UTCEPSS rescore
  62. 2026-08-06 11:19 UTCGHSA enrichment
  63. 2026-08-06 06:56 UTCGHSA enrichment
  64. 2026-08-06 02:33 UTCGHSA enrichment
  65. 2026-08-05 22:10 UTCEG score recompute
  66. 2026-08-05 22:10 UTCGHSA enrichment
  67. 2026-08-05 19:17 UTCEPSS rescore
  68. 2026-08-04 15:10 UTCEPSS rescore
  69. 2026-08-04 04:21 UTCGHSA enrichment
  70. 2026-08-03 23:56 UTCGHSA enrichment
  71. 2026-08-03 19:33 UTCEG score recompute
  72. 2026-08-03 19:33 UTCGHSA enrichment
  73. 2026-08-03 10:36 UTCEPSS rescore
  74. 2026-08-03 03:44 UTCGHSA enrichment
  75. 2026-08-02 22:44 UTCGHSA enrichment

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Frequently asked(5)

What is CVE-2026-25199?
CVE-2026-25199 is a critical vulnerability published on May 8, 2026. Instances deployed via the Proxmox extension allow unauthorized access to instances belonging to other tenants. This issue affects Apache CloudStack: from 4.21.0.0 through 4.22.0.0. The Proxmox extension for CloudStack improperly uses a user-editable instance setting, proxmox_vmid, to associate…
When was CVE-2026-25199 disclosed?
CVE-2026-25199 was first published in the National Vulnerability Database on May 8, 2026, with the most recent update on May 9, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-25199 actively exploited?
CVE-2026-25199 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 58.7% of all scored CVEs.
What is the CVSS score of CVE-2026-25199?
CVE-2026-25199 has a CVSS v3 base score of 9.1 (NVD).
How do I remediate CVE-2026-25199?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-25199, 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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