CVE-2026-66300

MEDIUMPre-NVD 5.05.0—
EchelonGraph scoreMEDIUM confidence

Score 5.0 from GitHub Security Advisory (severity: LOW) published 2026-08-04. A secondary CVSS source baseline 5.0; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this week
5.0EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 5.0Exploit: None knownExposed services: Not assessed

An upstream fix is merged but not yet released — mitigate (WAF / firewall / segmentation) until the release ships, then apply it.

SNOMED International Snowstorm contains a reflected XSS vulnerability within the "Web Route" redirection functionality. An attacker can inject arbitrary JavaScript which will execute upon a target user navigating to a crafted, malicious link. Fixed in 10.12.2 and 10.9.3.

CVSS v3
5.0
EG Score
5.0MEDIUMmedium confidence
EG Risk
27
EG Risk 27/100CISA SSVC

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
Severity50% × 45%
Exploitation0% × 40%
Automatability30% × 15%
CISA SSVC: Track at low or medium mission impact; Track or Attend at high (mission-essential systems).
Action: An upstream fix is merged but not yet in a tagged release. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high until it ships, then apply the release.
EPSS PROB
0.3%
EPSS %ILE
23rd
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track or Attend at high (mission-essential systems).

An upstream fix is merged but not yet in a tagged release. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high until it ships, then apply the release.

Exploitation none (no KEV listing, exploit record or EPSS ≥ 50%) · Automatable unknown (not published for this CVE) · Technical impact partial (CVSS below 9.0). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

August 4, 2026

Last Modified

August 26, 2026

Advisory Details (3)

Auto-updated Aug 4, 2026
Upstream fix merged — awaiting tagged release. Sources: github_commit.
generic
https://www.cve.org/CVERecord?id=CVE-2026-66300
github_commit

commit b8061add427c (IHTSDO/snowstorm)

Fix landed in IHTSDO/snowstorm commit b8061add427c — awaiting tagged release

https://github.com/IHTSDO/snowstorm/commit/b8061add427c930b3030549e77aa23ec5957ceb6
github_commit

commit 575b55569581 (IHTSDO/snowstorm)

Fix landed in IHTSDO/snowstorm commit 575b55569581 — awaiting tagged release

https://github.com/IHTSDO/snowstorm/commit/575b555695811110dafe2fcea7dd2fd7e4bcee39

Vendor Advisories for CVE-2026-66300(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 13× in last 7d / 60× 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 156 total refreshes for this CVE.

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

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-66300?
CVE-2026-66300 is a medium vulnerability published on August 4, 2026. SNOMED International Snowstorm contains a reflected XSS vulnerability within the "Web Route" redirection functionality. An attacker can inject arbitrary JavaScript which will execute upon a target user navigating to a crafted, malicious link. Fixed in 10.12.2 and 10.9.3.
When was CVE-2026-66300 disclosed?
CVE-2026-66300 was first published on August 4, 2026, with the most recent update on August 26, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-66300 actively exploited?
CVE-2026-66300 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (23rd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-66300?
CVE-2026-66300 has a CVSS base score of 5.0 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-66300?
An upstream fix for CVE-2026-66300 has been merged but is not yet in a tagged release. Until it ships, restrict network exposure of the affected system or apply the vendor's mitigation, then update to the release that contains the fix. The vendor advisories EchelonGraph has for CVE-2026-66300 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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