CVE-2026-23557

MEDIUMNVD 6.56.5—
EchelonGraph scoreMEDIUM confidence

Score 6.5 from GitHub Security Advisory published 2026-05-19. NVD baseline CVSS 6.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
6.5
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 6.5Exploit: NoneExposed: 0

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

Any guest can cause xenstored to crash by issuing a XS_RESET_WATCHES command within a transaction due to an assert() triggering.

In case xenstored was built with NDEBUG #defined nothing bad will happen, as assert() is doing nothing in this case. Note that the default is not to define NDEBUG for xenstored builds even in release builds of Xen.

CVSS v3
6.5
EG Score
6.5(medium)
EPSS
5.3%
KEV
Not listed

Published

May 19, 2026

Last Modified

May 19, 2026

Advisory Details (3)

Auto-updated Jun 14, 2026
No patch confirmed yet.
generic

XSA-484 - Xen Security Advisories

http://xenbits.xen.org/xsa/advisory-484.html
generic

oss-security - Xen Security Advisory 484 v2 (CVE-2026-23557) - Xenstored DoS via XS_RESET_WATCHES command

http://www.openwall.com/lists/oss-security/2026/04/28/11
generic

XSA-484 - Xen Security Advisories

https://xenbits.xenproject.org/xsa/advisory-484.html

Vendor Advisories for CVE-2026-23557(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 11× in last 7d / 66× 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 137 total refreshes for this CVE.

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

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-23557?
CVE-2026-23557 is a medium vulnerability published on May 19, 2026. Any guest can cause xenstored to crash by issuing a XSRESETWATCHES command within a transaction due to an assert() triggering. In case xenstored was built with NDEBUG #defined nothing bad will happen, as assert() is doing nothing in this case. Note that the default is not to define NDEBUG for…
When was CVE-2026-23557 disclosed?
CVE-2026-23557 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-2026-23557 actively exploited?
CVE-2026-23557 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 5.3% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-23557?
CVE-2026-23557 has a CVSS v3 base score of 6.5 (NVD).
How do I remediate CVE-2026-23557?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-23557, 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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