CVE-2026-23556

CRITICALPre-NVD 9.49.4—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.4 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.1%, top 97% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — 3 sources updated this week
9.4EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.4Exploit: None knownExposed: 0

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

When oxenstored is tearing a domain down, the node data is cleaned up but the usage counts are leaked.

When the domain ID is eventually reused, the new domain can create fewer nodes before beeing deemed to be over quota.

CVSS v3
9.4
EG Score
9.4(medium)
EG Risk
42(Track)
EG Risk 42/100SSVC: 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
Severity94% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
3%
KEV
Not listed

Published

July 9, 2026

Last Modified

July 9, 2026

Advisory Details (3)

Auto-updated Aug 23, 2026
No patch confirmed yet.
generic

XSA-483 - Xen Security Advisories

http://xenbits.xen.org/xsa/advisory-483.html
generic

oss-security - Xen Security Advisory 483 v2 (CVE-2026-23556) - oxenstored keeps quota related use counts across domain destruction

http://www.openwall.com/lists/oss-security/2026/04/28/10
generic

XSA-483 - Xen Security Advisories

https://xenbits.xen.org/xsa/advisory-483.html

Vendor Advisories for CVE-2026-23556(1)

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

Affected Packages

(4 across 4 ecosystems)
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 46× in last 7d / 216× 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 296 total refreshes for this CVE.

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

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-23556?
CVE-2026-23556 is a critical vulnerability published on July 9, 2026. When oxenstored is tearing a domain down, the node data is cleaned up but the usage counts are leaked. When the domain ID is eventually reused, the new domain can create fewer nodes before beeing deemed to be over quota.
When was CVE-2026-23556 disclosed?
CVE-2026-23556 was first published in the National Vulnerability Database on July 9, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-23556 actively exploited?
CVE-2026-23556 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 96.7% of all scored CVEs.
What is the CVSS score of CVE-2026-23556?
CVE-2026-23556 has a CVSS v3 base score of 9.4 (NVD).
How do I remediate CVE-2026-23556?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-23556, 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

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