CVE-2026-23558

HIGHNVD 7.87.8—
EchelonGraph scoreMEDIUM confidence

Score 7.8 from GitHub Security Advisory (severity: HIGH) published 2026-05-19. NVD baseline CVSS 7.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
7.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 7.8Exploit: NoneExposed: 0

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

The adjustments made for XSA-379 as well as those subsequently becoming XSA-387 still left a race window, when a HVM or PVH guest does a grant table version change from v2 to v1 in parallel with mapping the status page(s) via XENMEM_add_to_physmap. Some of the status pages may then be freed while mappings of them would still be inserted into the guest's secondary (P2M) page tables.

CVSS v3
7.8
EG Score
7.8(medium)
EPSS
2.0%
KEV
Not listed

Published

May 19, 2026

Last Modified

May 19, 2026

Advisory Details (3)

Auto-updated May 19, 2026
No patch confirmed yet.
generic

XSA-486 - Xen Security Advisories

http://xenbits.xen.org/xsa/advisory-486.html
generic

oss-security - Xen Security Advisory 486 v2 (CVE-2026-23558) - grant table v2 race in status page mapping

http://www.openwall.com/lists/oss-security/2026/04/28/13
generic

XSA-486 - Xen Security Advisories

https://xenbits.xenproject.org/xsa/advisory-486.html

Vendor Advisories for CVE-2026-23558(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 9× in last 7d / 72× 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 176 total refreshes for this CVE.

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

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-23558?
CVE-2026-23558 is a high vulnerability published on May 19, 2026. The adjustments made for XSA-379 as well as those subsequently becoming XSA-387 still left a race window, when a HVM or PVH guest does a grant table version change from v2 to v1 in parallel with mapping the status page(s) via XENMEMaddto_physmap. Some of the status pages may then be freed while…
When was CVE-2026-23558 disclosed?
CVE-2026-23558 was first published in the National Vulnerability Database on May 19, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-23558 actively exploited?
CVE-2026-23558 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 2.0% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-23558?
CVE-2026-23558 has a CVSS v3 base score of 7.8 (NVD).
How do I remediate CVE-2026-23558?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-23558, 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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