CVE-2020-15566

MEDIUMNVD 6.56.5—
EchelonGraph scoreMEDIUM confidence

Score 6.5 from GitHub Security Advisory published 2022-05-24. NVD baseline CVSS 6.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
6.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.5Exploit: None knownExposed: 0

A fix is available — apply it.

An issue was discovered in Xen through 4.13.x, allowing guest OS users to cause a host OS crash because of incorrect error handling in event-channel port allocation. The allocation of an event-channel port may fail for multiple reasons: (1) port is already in use, (2) the memory allocation failed, or (3) the port we try to allocate is higher than what is supported by the ABI (e.g., 2L or FIFO) used by the guest or the limit set by an administrator (max_event_channels in xl cfg). Due to the missing error checks, only (1) will be considered an error. All the other cases will provide a valid port and will result in a crash when trying to access the event channel. When the administrator configured a guest to allow more than 1023 event channels, that guest may be able to crash the host. When Xen is out-of-memory, allocation of new event channels will result in crashing the host rather than reporting an error. Xen versions 4.10 and later are affected. All architectures are affected. The default configuration, when guests are created with xl/libxl, is not vulnerable, because of the default event-channel limit.

CVSS v3
6.5
EG Score
6.5(medium)
EG Risk
34(Track)
EG Risk 34/100SSVC: 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
Severity65% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
34%
KEV
Not listed

Published

July 7, 2020

Last Modified

November 21, 2024

References (16)

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntuxen-system-armhf (4.11.3+24-g14b62ab3e5-1ubuntu2.3) @ focal2026-05-27ubuntu

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.

Weakness Classification(2)

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 13× in last 7d / 47× 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 102 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2020-15566?
CVE-2020-15566 is a medium vulnerability published on July 7, 2020. An issue was discovered in Xen through 4.13.x, allowing guest OS users to cause a host OS crash because of incorrect error handling in event-channel port allocation. The allocation of an event-channel port may fail for multiple reasons: (1) port is already in use, (2) the memory allocation failed,…
When was CVE-2020-15566 disclosed?
CVE-2020-15566 was first published in the National Vulnerability Database on July 7, 2020, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2020-15566 actively exploited?
CVE-2020-15566 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 66.5% of all scored CVEs.
What is the CVSS score of CVE-2020-15566?
CVE-2020-15566 has a CVSS v3 base score of 6.5 (NVD).
How do I remediate CVE-2020-15566?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2020-15566, 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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