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
7.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.8Exploit: None knownExposed: 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)
EG Risk
35(Track)
EG Risk 35/100SSVC: 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
Severity78% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
2%
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.

Affected Packages

(9 across 9 ecosystems)
Alpine:v3.20(1)
PackageVulnerable rangeFixed inDependents
xen—4.18.5-r7—
Alpine:v3.21(1)
PackageVulnerable rangeFixed inDependents
xen—4.19.5-r2—
Alpine:v3.22(1)
PackageVulnerable rangeFixed inDependents
xen—4.20.3-r2—
Alpine:v3.23(1)
PackageVulnerable rangeFixed inDependents
xen—4.20.3-r2—
Alpine:v3.24(1)
PackageVulnerable rangeFixed inDependents
xen—4.21.1-r3—
Debian:11(1)
PackageVulnerable rangeFixed inDependents
xen4.14.2+25-gb6a8c4f72d-2 ... 4.20.3+127-gc42374a105-1 (46 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
xen4.17.1+2-gb773c48e36-1 ... 4.20.3+127-gc42374a105-1 (25 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
xen4.20.0+68-g35cb38b222-1 ... 4.20.3+127-gc42374a105-1 (7 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
xen4.20.0+68-g35cb38b222-1, 4.20.2+37-g61ff35323e-1, 4.20.2+7-g1badcf5035-1, 4.20.2+7-g1badcf5035-24.20.3+127-gc42374a105-1—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 6× in last 7d / 59× 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 231 total refreshes for this CVE.

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

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 0% probability of exploitation in the next 30 days, which ranks it in the top 98.1% of all scored CVEs.
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.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-23558

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